Dental evolution in non-coelurosaur theropods

Dentition-based datamatrix

The evolution of the dentition in nc theropods was explored using a datamatrix of 44 discrete and similarly weighted dental characters, nine of which were ordered (char. 5-7, 14, 20, 23-24, 34-35), scored in 80 saurischian taxa. This new dataset is a variation of the dentition-based datamatrix created by Hendrickx & Mateus (2014a) and last updated by Hendrickx et al. (2025), whose primarily goal was to classify isolated theropod teeth using a cladistic analysis. Conversely, the new datamatrix was built to compile as much information on the external morphology of the theropod dentition using as few dental characters precisely to explore dental evolution in non-avian theropods. Many dental characters present in Hendrickx et al.’s (2024) datamatrix were, therefore, excluded or fused into a single character. Likewise, other characters omitted by Hendrickx et al. (2019, 2024, 2025) but used in studies exploring theropod relationships were considered in the dataset (e.g., morphological homodonty, isodont tooth generation, crown/skull ratio, as well as the presence and position of unserrated crowns, reduced or enlarged teeth, and closely packed or widely spaced teeth along the tooth row). Most dentulous nc theropods were included in this study, with only a few taxa excluded due to the extremely limited nature of their dental material (e.g., Alpkarakush, Condorraptor, Cryolophosaurus, Ekrixinatosaurus, Eoabelisaurus, Gojirasaurus, Magnosaurus, Rahiolisaurus, Sanjuansaurus, Siamosaurus), poorly preserved dentitions (e.g., Carnotaurus), or teeth represented solely by hatchlings (e.g., Lourinhanosaurus). Because the datamatrix uses theropod genera as operational taxonomic units (OTUs), the dentition of theropods known from more than one species (e.g., Allosaurus, Carcharodontosaurus, Ceratosaurus, Torvosaurus, Sinosaurus) was scored based on the dental material referred to all species. Novas’ (1994) opinion regarding the taxonomy of Herrerasaurus ischigualastensis was followed so that the dental material belonging to Frenguellisaurus ischigualastensis and Ischisaurus cattoi was considered as representing Herrerasaurus. Megapnosaurus rhodesiensis and “Syntarsus” kayentakatae, referred by some authors to Coelophysis, as well as Yangchuanosaurus shangyuensis and Yangchuanosaurus hepingensis were, however, considered as separate OTUs in the datamatrix. As done by Wang et al. (2017a), specimen BP/1/5278, thought to represent a possible juvenile Dracovenator by Yates (2005), was considered as representing a separate taxon. Likewise, because the holotypic specimen of Eocarcharia dinops was recently revealed to belong to a spinosaurid (Cau & Paterna, 2025), the name ‘Eocarcharia’ here refers to the maxilla MNBH GAD 7 and various isolated teeth ascribed to this genus by Sereno and Brusatte (2008), which genuinely represent a carcharodontosaurid taxon from the Lower Cretaceous of Niger (Kellermann et al., 2025; Cau & Paterna, 2025). Finally, because this study explores tooth loss in nc theropods, the two edentulous ceratosaurs Limusaurus and Berthasaura were included in the dataset. Given their extreme ontogenetic dental changes, the dentulous juveniles and toothless mature individuals of Limusaurus were, however, scored separately.

Studied specimens, dental nomenclature, and phylogenetic definitions

The scoring of the dental characters primarily relies on firsthand examinations of the dentition of 50 saurischian taxa (62.5% of the taxa included in this study) deposited in the collections of 40 scientific institutions from Argentina, Brazil, Canada, China, France, Italy, Germany, Portugal, Qatar, Spain, South Africa, Switzerland, the United Kingdom, and the United States (see Supplementary material). Holotypes were accessed in person in most of these taxa but the dental morphology of referred specimens was also examined. Isolated shed teeth non-associated with holotypes but confidently referred to genera were also considered in this study (see Supplementary material). Anatomical observations of minute dental structures such as denticles and enamel surface texture were assisted with the use of an AM411T Dino-Lite Pro digital microscope. The dentition of a further 20 non-avian theropod taxa was scored using high-quality casts (3), 3D-models (3), and/or highresolution photographs provided by colleagues (14). Publications with detailed descriptions and/or illustrations of the dentition were finally used to score an additional ten taxa whose teeth could not be examined personally (see Supplementary information). No histological, FEA, or isotopic studies were conducted in this study, which primarily relies on external features of the theropod dentition.

The anatomical, positional, directional, and morphometric nomenclature used in this study follows the dental terminology proposed by Hendrickx et al. (2015c), which is mostly based on the nomenclature and abbreviations provided by Smith et al. (2005) and the directional terminology proposed by Smith & Dodson (2003). Dental terms related to the inclination of the tooth crowns within the jaws (i.e., decumbency, procumbency, and retrocumbency) follow the definitions given by Hendrickx et al. (2019). Quantitative data used in the characters such as the height (CH), elongation of the crown (CHR), compression of the tooth at the crown base (CBR) or denticle densities (DC) follow the measurement method detailed by Hendrickx et al. (2015c) and largely based on the methodology proposed by Smith et al. (2005). However, the methodology used to measure crown height and denticle density along the carinae follows that adopted by Hendrickx et al. (2020a, supplementary information). The denticle crown ratio (DCR), a variable recently proposed by Hendrickx et al. (2025) to quantify the size of the denticles in relation to the height of crown, is also used in this study. DCR corresponds to the quotient of the largest distal denticle length (DDL) by the crown height (CH) multiplied by a hundred (DCR=DDL/CH*100; DCR=[5/DC]/CH*100) so that the crowns of theropods with minute denticles (e.g., Baryonychinae) have a DCR lower than 0.5 whereas those with particularly large denticles (e.g., Noasaurus, Sciurumimus) have a DCR higher than 4. Finally, the phylogenetic definitions compiled by Hendrickx et al. (2015a, 2024, 2025) for non-tetanuran theropods and Rauhut & Pol (2019) for tetanurans (e.g., Allosauroidea, Carnosauria, Megalosauroidea, Piatnitzkysauridae) are adopted in this study.

Dental evolution analysis

We followed the same methodology as Hendrickx et al. (2019, 2025) and explored the nc theropod dental evolution by mapping dental apomorphic features on six topological trees representing alternative phylogenetic hypotheses of theropod evolution. The first topological tree (Tree 1), which includes all OTUs, is a combination of the results of the recent phylogenetic analyses focused on major theropod subclades such as Coelophysoidea, Ceratosauria, and Carnosauria. This tree hypothesizes herrerasaurids as early branching saurischians, elaphrosaurines as early branching coelurosaurs and allosauroids among averostrans and excluding megaraptorans. It is based on the results of the analyses performed by Moro et al. (2024) for non-theropod saurischians, Ezcurra et al. (2023) for non-averostran theropods (with BP/1/5278 classified as the sister taxon of Megapnosaurus rhodesiensis) using Cau’s (2024) results for the position of Notatesseraeraptor, Dracovenator, Sinosaurus and Chilesaurus, Hendrickx et al. (2024) for Ceratosauria (with Saltriovenator as the sister taxon of Berberosaurus, as recovered by Dal Sasso et al. 2018), and Chenanisaurus in a polytomy with Kryptops, as found by Longrich et al. (2017), and Kellerman et al.’s (2025) split dataset for Megalosauroidea and Allosauroidea (with Erectopus as an early branching allosauroid, as recovered by Cau 2024). The second tree (Tree 2) includes most OTUs and is also a combination of the results of other also recent cladistic analyses focused on major nc theropod subclades. This tree postulates a phylogenetic position of herrerasaurids among Theropoda, elaphrosaurines within Noasauridae, megalosauroids among Carnosauria, and megaraptorans within Allosauroidea. It is based on the results obtained by Marsh & Rowe (2020) for non-averostran theropods (also seen in Marsh & Parker 2020), Pol et al., (2024) for Ceratosauria, and Pradelli et al. (2025) for Megalosauroidea and Allosauroidea. The four remaining trees strictly follow the topological trees resulting from the phylogenetic analyses performed by Cau (2024) using the “Ontogenetic State Partitioning” (here abbreviated OSP) protocol, in which juvenile and mature OTUs are scored separately (Tree 3), and the “Semaphoront Coding Test” (SCT), in which both juvenile and mature OTUs are coded with non-ontogenetic-contingent restrictions (Tree 4), as well as Kellerman et al. (2025) dataset from the Mesozoic Tetrapod work group, using their split (Tree 5) and merged datasets (Tree 6). Character distributions for ambiguous and non-ambiguous apomorphic dental features were visualised on each tree using TNT 1.5 (Goloboff & Catalano, 2016), Mesquite 3.4 (Maddison & Maddison, 2017) and WinClada 1.00.08 (Nixon, 2002) based on the Nexus file created with Mesquite 3.4.

Summary

- The rise of theropods in the Late Triassic, as well as the radiation of all major nc theropod clades in the Late Triassic and Early Jurassic (i.e., Coelophysoidea, Ceratosauria, Megalosauroidea, and Allosauroidea) was only accompanied by minor or no changes at all in their dentition.

- The early dental evolution of theropod dinosaurs is characterised by an enlargement of mesial dentary teeth in neotheropods, an anterior displacement of the distal extension of the upper tooth row at the level of the lachrymal in non-coelophysoid neotheropods, and possibly the loss of pterygoid teeth in theropods more derived than Eodromaeus and the development of a short subnarial gap in coelophysoids.

- The first important dental change, which probably resulted from a dietary shift towards the consumption of larger prey items, occurred during the radiation of the clade Dilophosaurus + Averostra and includes a reduction in dentary (<18) and maxillary (<15) tooth count, an increase in maxillary crown height (>3 cm), and an enlargement of the distal denticles in lateral teeth (<15 de/5mm).

- Edentulism occurred once, possibly twice in Ceratosauria. Based on the ontogenetic edentulism of Limusaurus, complete tooth loss in ceratosaurs was likely preceded by tooth simplification (i.e., loss of carinae and denticles), the loss of premaxillary and dentary teeth anteriorly, and the loss of maxillary teeth posteriorly. The gradual loss of teeth in ceratosaurs was accompanied by the progressive development of a keratinised rhamphotheca leading to a fully beaked toothless skull.

- Dental evolution in ceratosaurs was marked by an increase in lateral crown height (>6 cm) in ceratosaurids, the development of procumbent lanceolate fluted dentary teeth in at least some noasaurines as well as an increase in the number of dentary teeth and a weaker variation of crown size along the maxillary tooth row in abelisaurids.

- One of the two most significant shifts in nc theropod dental evolution took place during the radiation of the clade encompassing the putative tetanuran Chilesaurus, characterised by its highly derived folidont dentition adapted for herbivory. Chilesaurus may represent an unrecognised theropod clade potentially confined to the southernmost regions of South America during the Late Jurassic and exhibiting a feeding ecology distinct from that of other early branching tetanurans.

- A few dental changes mainly related to the reduction or increase in the number of premaxillary, maxillary, and dentary teeth as well as variation in denticle morphology and crown ornamentation occurred during the evolution of most non-spinosaurid carnosaur clades.

- Dental evolution in non-spinosaurid megalosauroids includes a notable difference in size between mesial and distal denticles in piatnitzkysaurids and a dentary with less than 15 tooth positions in megalosaurids.

- A shift in feeding habit from a carnivorous to a primarily piscivorous diet (here referred to the consumption of aquatic prey items) best explain the second major shifts in nc theropod dental evolution and the drastic change in the dentition of spinosaurids made of more than five premaxillary tooth positions, conidont teeth exhibiting the same morphology along the tooth row but changing dramatically in size in the mesial portion of the jaws, as well as fluted crowns with minute denticles or unserrated carinae and veined to anastomosed enamel surface texture.

- Some Middle Jurassic metriacanthosaurids from Asia convergently developed fluted teeth likely well-before spinosaurids and ceratosaurs. Unlike spinosaurids which were unequivocally piscivorous, the presence of tall ziphodont lateral crowns with comparatively large denticles suggests that the fluted teeth of metriacanthosaurids probably evolved to stabilize a lethal bite in a large struggling prey.

- The most important dental changes in allosauroids occurred during the emergence of carcharodontosaurines with tall (>6 cm) strongly compressed and poorly distally recurved crowns showing large (<9 de/5mm) denticles, mesiodistally wide apices, and a small constriction at the crown-root transition, a dental transition interpreted as reflecting a shift toward a more specialised carnivorous feeding strategy, potentially involving an increased dependence on scavenging.

Non-averostran Theropoda

The presence of at most one apomorphic dental character supporting the clade Theropoda (Figs 5-6) indicates that the emergence of theropods from early-diverging saurischians in the Late Triassic was not marked by significant changes in dental morphology. Indeed, the ziphodont dentition made of laterally compressed blade-shape lateral teeth with mesial and distal denticles and plesiomorphically present in earliest branching saurischians (e.g., herrerasaurids, Buriolestes, Tawa, Eodromaeus) was retained in unquestionable early branching theropods such as coelophysoids, Dracoraptor, and Zupaysaurus (Ballell et al., 2022). In contrast to certain early-diverging saurischians like Daemonosaurus, whose dentition markedly deviated from the isodont condition typical of other dinosaurs (Nesbitt & Sues, 2020), the dentition of most early branching theropods appears to have only slightly diverged from this ancestral morphology. It is worth noting that while Daemonosaurus exhibits autapomorphic features such as an enlarged mesial dentition, its fluted lateral crowns and basally constricted crown bases are shared with Tawa and earliest diverging sauropodomorphs (e.g., Buriolestes, Eoraptor), respectively. The distribution of numerous dental apomorphies near the base of the theropod clade remains uncertain, largely due to the incomplete dentitions of several early branching taxa (e.g., Anteavis, Dracoraptor, Dracovenator, Liliensternus, Panguraptor, Tawa) and ongoing disagreements regarding early theropod phylogeny. This applies to the loss of pterygoid teeth, which might characterize Theropoda when Eodromaeus lies outside the clade (Tree 1) and Neotheropoda if Eodromaeus is recovered as the sister taxon of neotheropods (Tree 2). The recent publication of Anteavis, which is devoid of pterygoid teeth (Martínez et al., 2025), however, suggests that a palatal dentition was lost in theropods more derived than Eodromaeus (i.e., which corresponds to the clade Anteavis + Lepidus + Neotheropoda in Martínez et al., 2025). This remains, however, ambiguous owing to the fact that the presence of pterygoid teeth in Tawa, whose position among dinosaurs remains unsettled, is currently unknown. However, most classifications agree with an increase in size of the mesial dentary teeth (char. 10:1; Trees 1-2, 4; Figs 5A, 6B) in neotheropods while the development of mesial denticles in mesial teeth (char. 30:0; Trees 2, 5; Fig. 6) and an anterior displacement of the posteriormost maxillary tooth, which is aligned to the lachrymal or very close to it (char. 14:1; Trees 3-6; Figs 5A, 6A), are apomorphic to non-coelophysoid neotheropods in some topologies.

Coelophysoidea, the first theropod radiation from the Late Triassic and Early Jurassic (Hendrickx et al., 2015a; Martínez Apaldetti 2017; Kirmse et al. 2023; Martínez et al., 2025), has a dentition characterised by a high number of maxillary (20-29) and dentary teeth (18-25; Table 1), retrocumbent (i.e., posteriorly inclined crowns projecting backward; Hendrickx et al., 2019) premaxillary teeth, procumbent mesial maxillary and dentary teeth, enlarged mesial dentary teeth, unserrated or only distally denticulated mesial teeth, and a short subnarial gap (Hendrickx et al., 2019). All of these dental features are, however, shared with other early branching saurischians such as Buriolestes (e.g., distally unserrated mesial teeth, retrocumbent premaxillary teeth, procumbent mesial maxillary and dentary teeth, subnarial gap, high number of maxillary and dentary teeth; Table 1) or other early branching neotheropods (enlarged mesial dentary teeth). A short subnarial gap (char. 15:1) is, however, synapomorphic to Coelophysoidea when the latter is recovered more derived than Eodromaeus (absent) and more basal than the clade encompassing Liliensternus (n.b., it is unknown in Liliensternus and Zupaysaurus while Dilophosaurus has an extensive subnarial gap; Tree 2; Fig. 6B). The dentition of coelophysoid theropods also appears to have remained unchanged throughout their evolution. Only the possible derived clade made of Coelophysis and Megapnosaurus rhodesiensis (Trees 2, 5-6; Fig. 6) shows the apomorphic dental condition of having more than 30 distal denticles per 5 mm (char. 34:0), which may relate to their smaller size. Coelophysoids were agile and gracile small to medium-bodied (1.5-3 metres in length) theropods with long snouts, slender and narrow skulls, elongated neck, and short forelimbs ended with three-fingered hands bearing sharp claws (Tykoski Rowe 2004; Hendrickx et al., 2015a; Nabavizadeh & Weishampel, 2023). Stomach contents in Coelophysis (Nesbitt et al., 2006) and Megapnosaurus (Raath 1977), as well a coprolites in the former (Rinehart et al., 2009), indicate that their dentition made of small denticulated lateral teeth and unserrated retrocumbent premaxillary and procumbent mesial dentary teeth was well-suited to feed on small prey items such as early crocodylomorphs, lizard-like vertebrates, and possibly fish and juveniles of their own species.

The first major dental change in the dentition of theropods occured during the radiation of the clade made of Dilophosaurus + Averostra (Figs 5-6) in the Early Jurassic. This transition was marked by a reduction in dentary tooth count to fewer than 18 (char. 7:2; Table 1), an increase in crown height exceeding 3 cm (char. 20:2), and an enlargement of the distal denticles either to less than 15 de/5mm (char. 34:2) or compared to crown height (DCR>0.5; char. 35:1). Maxillary tooth loss also occurred during the evolution of early branching neotheropods, but due to the incompleteness of the maxillae of Dracovenator and Liliensternus, it remains unclear when the reduction in maxillary tooth count to fewer than 15 took place (Table 1). These notable dental changes in early neotheropod evolution seem to be more closely associated with a shift in feeding ecology than with an increase in body size. Indeed, a body size increase from smaller early branching theropods (<3 m), such as coelophysoids, Dracoraptor, and probably Tawa and Eodromaeus, had already taken place in a few early-branching non-coelophysoid neotheropods such as Zupaysaurus (5–6 m; Paul, 2024), Liliensternus (4–7, possibly up to 9 m; Paul, 2024; Mujal et al., 2025) and Dracovenator (6–7 m; Paul, 2024), which are consistently placed outside the clade formed by Dilophosaurus and more derived neotheropods in most phylogenetic analyses [n.b., the anterior displacement of the last maxillary tooth at the level of the lachrymal (char. 14:1), combined with a decrease in distal denticle density to less than 16 denticles per 5mm (char. 34:2), however, appear to be associated with an increase in body-size in Cau’s (2024; OSP) topology using a dataset where juveniles and adults were scored separately (Tree 3; Fig. 5B) and where Zupaysaurus and Dracovenator are classified as a derived coelophysoid and a dilophosaurid, respectively]. Conversely, although the feeding ecology of many carnivorous neotheropods remains poorly understood, coelophysoids and other early-branching neotheropods like Notatesseraeraptor seem to have had similar diets consisting mainly of small to medium-sized prey, whereas Dilophosaurus and Sinosaurus likely also targeted larger prey such as early branching sauropodomorphs and possibly even other members of their own species (Raath, 1977; Paul, 1988; Dong, 2003; Nesbitt et al., 2006; Milner & Kirkland, 2007; Xing, 2012; Zahner & Brinkmann, 2019; Marsh & Rowe, 2020). A reduction of the maxillary and dentary tooth count also seems to correlate with the consumption of larger prey items given that large-bodied carnivorous theropods such as ceratosaurids, megalosaurines, carcharodontosaurids, and tyrannosaurids tend to have a lower number of maxillary and dentary teeth compared to smaller mesopredators (Table 1; C.H. pers. obs.).

Ceratosauria

The classification of the neotheropod Sinosaurus from the Early Jurassic of China (Xing, 2012; Xing et al., 2013; Zhang et al., 2024; Liang et al., 2025) has a significant impact on the dental evolution of Averostra (Ceratosauria + Tetanurae). The radiation of averostrans is indeed characterised by the loss of retrocumbent premaxillary teeth (char. 16:0) when Sinosaurus is classified as the sister taxon of Tetanurae (Trees 1-2; Figs 5A, 6B), the loss of retrocumbent premaxillary teeth and the enlargement of mesial dentary teeth (char. 10:0) when it represents the earliest branching tetanuran (Tree 2; Fig. 6B), and a decrease in the number of dentary teeth to 15 (char. 7:1; Table 1) when Sinosaurus is recovered as an early branching tetanuran more derived than Chilesaurus (Tree 3; Fig. 5B). Nc averostrans other than spinosaurids and the early branching tetanurans Chilesaurus and Sinosaurus are indeed characterised by a decumbent (i.e., teeth with no inclination; Hendrickx et al., 2019) dentition whereas Sinosaurus and most early branching averostrans share the apomorphic feature of having a relatively isodont dentition made of ten to 14 dentary teeth, two conditions also present in ceratosaurids, noasaurids, megalosaurids and the putative allosaurid Asfaltovenator.

Similar to Sinosaurus, the phylogenetic position of Limusaurus, the only elaphrosaurine ceratosaur known from cranial and dental material, either at the base of the ceratosaur clade (Tree 1; Fig. 7A), among Noasauridae (Trees 2, 5; Fig. 8), or within Neoceratosauria and closely related to Berthasaura (Tree 3; Fig. 7B) or slightly more derived than the latter (Tree 4), greatly influences the dental evolution of ceratosaurs. No dental apomorphy, nonetheless, diagnose Ceratosauria in all of these topologies, indicating that no important dental changes occurred during the radiation of ceratosaurs. Conversely, the complete loss of teeth in ceratosaurs is logically influenced by the phylogenetic positions of the two edentulous ceratosaurs Limusaurus and Berthasaura. They were recovered within the clade Noasauridae (in a large polytomy) and the more inclusive noasaurid clade Elaphrosaurinae by Hendrickx et al. (2024) using the datasets of Baiano et al. (2023) and Rauhut & Pol (2019), respectively, whereas Cau (2024) found Berthasaura and Limusaurus forming the sister-clade of Abelisauroidea and more derived than Elaphrosaurinae (Fig. 7B). In these scenarios, the loss of teeth would have likely occurred only once in Ceratosauria, either during the emergence of Elaphrosaurinae or the radiation of another unknown clade sister to abelisauroids. Berthasaura and Limusaurus are, however, distantly related in the phylogenetic trees obtained by De Souza et al. (2011), Hendrickx et al. (2024) based on Agnolín et al.’s dataset, and Cau (2024) using his dataset where juveniles and adults are scored the same way, suggesting that edentulism may have occurred twice during the evolution of ceratosaurs, as suggested by De Souza et al. (2021). In these scenarios, the dentition of ceratosaurs would have indeed been lost independently in elaphrosaurines and berthasaurines based on Hendrickx et al.’s (2024) tree or in two separate lineages of neoceratosaurs and noasaurids based on Cau’s (2024) and de Souza et al.’s (2021) phylogenetic trees, respectively. The presence of simple unserrated teeth in juvenile Limusaurus suggests that the loss of teeth in toothless ceratosaurs, whose step can be traced during the ontogenetic development of Limusaurus, was preceded by simplification of the dentition such as the loss of carinae and denticles (Wang et al., 2020). Ontogenetic edentulism in Limusaurus also shows that the teeth in ceratosaurs were first lost anteriorly in the premaxilla and dentary, and posteriorly in the maxilla, then anteriorly and posteriorly in the maxilla and dentary, before being fully lost in these three tooth-bearing bones (Wang et al., 2020). The loss of teeth in adult Limusaurus and Berthasaura was explained by a dietary shift towards herbivory (Xu et al., 2009; de Souza et al., 2021), an hypothesis supported by the presence of a gastric mill and isotopic data in Limusaurus (Wang et al. 2017a).

In dentulous ceratosaurs, the emergence of Ceratosauridae (Ceratosaurus + Genyodectes) in the Jurassic was marked by an increase in size of lateral teeth, with a crown height exceeding six centimetres (char. 20:2; Figs 7, 8A). Depending on the position of Limusaurus, Berberosaurus, and Saltriovenator, it may also have been accompanied by the development of strongly compressed lateral crowns (CBR<0.4; char. 23:0; Tree 1) and subquadrangular denticles on the mesial carina of lateral teeth (char. 37:1; Tree 1; Fig. 7A). Ceratosaurids are well-known to have particularly tall maxillary teeth, with crowns surpassing the height of the dentary (Rauhut 2004; Pradelli et al. 2024). Henderson (1998) proposed that the tall and elongated maxillary teeth of Ceratosaurus may have been related to interspecific recognition or played a role in intraspecific behavior. In comparing the low skulls of Ceratosaurus with that of dogs, known for delivering rapid, slashing bites to wound and harass prey, he also suggested that the long and broad lateral crowns of Ceratosaurus, which he regarded as a scavenger feeding on different parts of carcasses than Allosaurus to minimize competition, would have produced greater frictional resistance during penetration and were propelled by powerful jaw abductor muscles (Henderson, 1998). Snively & Russel (2007) reached the same conclusions based on the large neck muscles, interpreting Ceratosaurus as a slice and rake feeder, i.e., a predator that used rapid, slashing strikes with its jaws when engaging large preys, raking through them with its large upper teeth. Biomechanical studies on the mandible led Therrien et al. (2005) to suggest that the asymmetrical premaxillary crowns, associated with the stout nature of the premaxillae and the upturned symphyseal region of the dentary, indicated that the jaw extremity in Ceratosaurus played a significant role, possibly in the capture and handling of smaller prey. Unlike Genyodectes, Ceratosaurus developed fluted mesial teeth, a feature typically associated with a piscivorous diet (Hendrickx et al., 2019) and which may have evolved independently in noasaurids such as Masiakasaurus (Carrano et al., 2002). Their presence in the conical mesial teeth of Ceratosaurus led Yun (2019) to postulate a higher proportion of fish in the diet of this ceratosaurid, which he viewed as an opportunist and generalist carnivore. Ichtyophagy in Ceratosaurus appears to be supported by sedimentological and taphonomic data, with Bakker & Bir (2005) observing that Ceratosaurus shed teeth were commonly associated with aquatic carcasses but rarely with sauropod remains, suggesting that although this theropod with tall ziphodont lateral teeth was probably capable of feeding on large dinosaurs like sauropods, it likely specialised in aquatic prey such as lungfish and crocodiles.

The dental evolution of abelisauroids was characterised by the development of normally compressed lateral crowns (0.4 < CBR ≤ 0.6; char. 23:1) and larger distal denticles compared to the crown height (DCR>1; char. 35:2-3) when Limusaurus is classified as an elaphrosaurine among Noasauridae (Tree 2; Fig. 8A). The dentition of noasaurines (i.e., Noasaurus, Masiakasaurus, Vespersaurus) remains too poorly known to draw any conclusions on dental evolution in this clade. The exclusion of Vespersaurus, whose dentition is currently limited to a single putative isolated mesial crown (Langer et al., 2019; Barbosa et al., 2023), from the analysis, however, reveals that the noasaurid dentition is diagnosed by the presence of mesial denticles significantly smaller than the distal ones (DSDI>1.2; char. 36:3; Tree 3; Fig. 7B) in crowns from the lateral and possibly mesial dentition (unknown in Noasaurus). Interestingly, five to seven apomorphic dental features constrain the two Gondwanan noasaurines, indicating that both evolved a specialised dentition separately in the latest part of the Cretaceous. The derived features characterizing the dentition of Noasaurus include the presence of maxillary crowns of less than 1 cm (char. 20:0), weakly elongated (CHR ≤ 2; char. 24:0), and slightly distally recurved (char. 27:1), 16 to 29 distal denticles per 5 mm at midcrown (char. 34:1), a DCR of more than 3.5 (char. 35:4), and in other topologies a crown skull ratio of less than 3 (char. 22:0) and the absence of transverse undulations on lateral crowns (char. 43:0; Figs 7-8). As for Masiakasaurus, its particularly apomorphic dental anatomy encompasses an heterodont dentition made of ziphodont and folidont crowns (char. 12:4), a skull crown ratio between 7 and 9 (char. 22:2), strongly elongated lateral crowns (char. 24:2), the presence of mesial and distal denticles in some but not all mesial teeth (char. 30:1), hooked distal denticles (char. 39:1), fluted mesial and some lateral teeth (char. 41:3), and a braided texture of the enamel (char. 44:1; Figs 7-8). Several noasaurids from the latest Cretaceous of Gondwana, i.e., Masiakasaurus (Carrano et al., 2002, 2011) and an Indian form (Mohabey et al., 2024), additionally evolved procumbent mesial dentary teeth and, if the dentary dentition of the Indian species is revealed to be similar to that of Masiakasaurus, spatulated (i.e., basally constricted), fluted mesial dentary teeth with minute denticles and a salinon-shaped cross-sectional outline at crown-base (Hendrickx et al., 2024). Masiakasaurus was interpreted by Sampson et al. (2001) and Carrano et al. (2002) as a possible piscivore or insectivore owing to the combination of procumbent fluted mesial crowns probably used in prehension and ziphodont lateral teeth used in cutting or slicing animal tissues. Based on the small ziphodont maxillary teeth of noasaurines and the numerous dental features shared between Masiakasaurus and spinosaurids, combined with the enlarged and strongly curved manual ungual I, Hendrickx et al. (2024) further postulated that noasaurines were opportunistic carnivores feeding on small prey items and probable piscivores.

Abelisaurids are well-known to have a diagnostic dentition made of relatively large (CH>2 cm) poorly recurved crowns with a straight or convex distal profiles, denticulated mesial and distal carinae extending to the root, irregular enamel surface texture and, in mesial teeth, a salinon-shaped cross-section outline at the crown base (Smith, 2007; Hendrickx & Mateus, 2014a; Hendrickx et al., 2020b, 2025). This study shows that their early dental evolution was characterised by a posterior displacement of the tallest maxillary crowns towards the middle portion of the maxilla (char. 21:1; Trees 1-3; Figs 7, 8A), a weaker variation of the crown size along the maxillary tooth row (char. 9:4; only revealed with the exclusion of Vespersaurus; Tree 3; Fig. 7B), and an increase in the number of dentary teeth to more than 14 (char.7:2; Table 1) when Limusaurus is classified outside noasaurids (Trees 1, 3-4; Fig. 7). Dental evolution was then marked by the loss of markedly distally recurved lateral crowns (char. 27:1) and enamel undulations (transverse and/or marginal undulations; char. 43.0) in abelisaurids more derived than the Early Cretaceous form Spectrovenator, as well as the development in lateral teeth of subquadrangular mesial denticles (char. 37:1) in abelisaurines (Abelisaurus, Aucasaurus, and Skorpiovenator). Dental evolution in Abelisauridae was recently examined in detail by Hendrickx et al. (2025), who analyzed a datamatrix of 148 discrete dentition-based characters scored across 22 ceratosaur taxa, including 13 abelisaurids. These authors similarly observed that the dental evolution of abelisaurids in the Early Cretaceous was characterised by shifts in dental proportions, notably a reduction in the size of the mesialmost dentary teeth and the displacement of the tallest crowns to the mid-portion of the maxilla (Hendrickx et al., 2025). The evolution of the dentition in abelisaurids was also characterised by an increase in the number of dentary tooth positions to more than 15 and the development of interdenticular sulci between distal denticles in mesial teeth when elaphrosaurines represent an early branching radiation of ceratosaurs. In Late Cretaceous forms, they found that a development of mesialmost and mid-maxillary teeth of similar size occurred in abelisaurids more derived than Rugops while an increase in crown height to more than three centimetres happened during the emergence of the clade Brachyrostra + Majungasaurinae (Hendrickx et al., 2025). Dental evolution among abelisaurid subclades finally involved subtle changes such as the development of subquadrangular mesial denticles in lateral teeth in brachyrostrans and poorly developed interdenticular sulci between distal denticles in abelisaurines (Hendrickx et al., 2025). In some Gondwanan abelisaurids such as Majungasaurus, the evolution of robust premaxillary teeth and a brachydont (i.e., short-crowned sensu Smith et al., 2005; Smith 2007) dentition, together with the development of a broad and abbreviated skull, fused and hypermineralised skull elements, high bite forces, and expanded occiput and neck musculature, were interpreted by Sampson & Witmer (2007) as adaptations to a bite-and-hold predatory strategy, whereby massive wounds were inflicted by an ambush predator on a large-bodied prey (such as titanosaur sauropods) through a few prolonged penetrating bites and powerful neck retraction. A different feeding strategy seems, however, to have evolved in European abelisaurids like Arcovenator, which display tall, strongly recurved lateral crowns characterised by a distal carina markedly deflected labially, a mesial carina restricted to part of the crown, and mesial denticles significantly smaller than the distal ones (DSDI>1.2; Hendrickx et al., 2020b, 2025). This suite of dental features, convergently present in piatnitzkysaurid tetanurans, may indicate a similar predatory lifestyle between these two distantly related avetheropod clades (Hendrickx et al., 2019, 2025).

Megalosauroidea and other early branching Tetanurae

No dental apomorphy diagnoses the clade Tetanurae. Conversely, the presence of zero to one dental apomorphy, namely a distalmost maxillary tooth aligned with the antorbital fenestra (character 14:2; Tree 2; Fig. 9B) or a mesial carina restricted to the apical part of the crown (char. 32:0; Tree 3: Fig. 10), serves as a diagnostic feature of the clade Orionides, contingent upon the inclusion of the putative earliest branching tetanuran Chilesaurus for which the distal extension of the upper dentition in unknown. An anterior displacement of the distal end of the upper tooth row throughout the evolution of theropods was already observed and discussed by Gauthier (1986: char. 38) and Rauhut (2003: char. 70). The distalmost maxillary tooth is ancestrally aligned to the orbit in the earliest branching theropods and coelophysoids (Fig. 6A), to the lachrymal in non-coelophysoid neotheropods and ceratosaurs (Fig. 5B, 6A), and to the antorbital fenestra in the large majority of non-maniraptoriform orionides (Fig. 9B). The upper tooth row even extends distally at the same level or anterior to the antorbital fenestra in Spinosaurus (Fig. 9B), early branching ornithomimosaurs, and oviraptorosaurs. The most extreme condition was achieved by the early branching oviraptorosaur Caudipteryx, which lost the maxillary teeth entirely but retained a few premaxillary teeth all anterior to the external naris (IVPP V12430).

With 12 dental autapomorphies, the possible tetanuran Chilesaurus shows a remarkably derived dentition which differs from that of other early branching tetanurans by the following dental features: a procumbent upper and lower dentition (char. 16:5), tiny teeth of less than 1 cm (char. 20:0), extremely elongated crowns (CHR > 2.5; char. 24:2), a weak mesial constriction between crown and root in all teeth (char. 25:3), straight crowns (char. 27:2), a fully lingually displaced mesial carina in mesial teeth (char. 28:3), denticles restricted to the mesial carina in a few mesial teeth (char. 30:3), denticles absent from the mesial carina in most lateral teeth (char. 31:4), a distal carina terminating well above the cervix in all teeth (char. 33:1), minute denticles (≥30 de/5mm; char. 34:0), vertically subrectangular distal denticles (char. 38:0), and the absence of transverse undulations (char. 43:0). The folidont dentition of Chilesaurus made of tiny crowns with minute denticles restricted to the crown apex, and convergently similar to that of some sauropodomorphs and therizinosaurs, was interpreted by Novas et al. (2015) as an adaptation towards an herbivorous feeding habit. These authors further postulated that Chilesaurus represented a unique theropod lineage endemic to the southern South America during the Late Jurassic, providing additional support for a dietary diversification towards herbivory among early branching theropods, as also occurred in ceratosaurs during the Late Jurassic (Limusaurus) and Cretaceous (Berthasaura). However, several authors (Baron & Barrett 2017, 2018; Müller & Dias-da-Silva 2019; Baron 2024) recovered Chilesaurus as an early branching ornithischian, offering additional support for the Ornithoscelida hypothesis (Ornithischia + Theropoda) of dinosaur relationships originally proposed by Baron et al. (2017). Cau (2024), however, found Chilesaurus as a tetanuran based on a datamatrix incorporating both theropods and early branching ornithischians. Furthermore, a thorough examination of Chilesaurus’ anatomy, along with additional phylogenetic analyses using diverse datasets focused on dinosaur, ornithischian, sauropodomorph, and theropod relationships, led Chimento (2018) to confirm its placement within Tetanurae, reinforcing the existence of a previously unrecognised herbivorous tetanuran clade, here informally referred as “chilesaurs”, restricted to the southern part of South America during the Jurassic.

The relationship of carnosaurs (i.e., megalosauroids and allosauroids) has changed dramatically over the past few years. Megalosauroidea, as recovered by some authors (Carrano et al., 2012; Cau, 2024; Kellermann et al., 2025), includes Piatnitzkysauridae and forms the sister clade of Avetheropoda (= Allosauroidea + Coelurosauria) whereas in other analyses (Rauhut & Pol 2019; Rauhut et al., 2024) Piatnitzkysauridae is found outside Megalosauroidea, either as the earliest branching tetanuran clade or as earliest branching allosauroids within the clade Carnosauria (Megalosauroidea + Allosauroidea). Dental evolution in megalosauroids and allosauroids is logically affected by these two different phylogenetic hypotheses, with Megalosauroidea being diagnosed by a mesial carina restricted to the apical part of the crown (char. 32:0) when it is classified among Carnosauria (Tree 2; Fig. 9B) while no apomorphic dental features support this clade when sister to Avetheropoda (Tree 1, 3; Figs 9A, 10). In both scenarios, minor changes took place during the early dental evolution of megalosauroids in the Middle and Late Jurassic. Dental evolution is characterised by a reduction in the size of mesial denticles (char. 36:3) in piatnitzkysaurids (Fig. 9A) and, in megalosaurids, a decrease in the number of dentary teeth (char. 7:1; Table 1), an increase in maxillary crown height compared to skull length (char. 22:2), and possibly a displacement of the mesial carina toward the apex of the crown when the clade is resolved (Tree 1; Fig. 9A).

Piatnitzkysauridae (i.e., Piatnitzkysaurus + Marshosaurus) is diagnosed by a size discrepancy between mesial and distal denticles (DSDI>1.2) in mesial and lateral teeth (char. 36: 3) in the two trees in which this clade is revolved (Trees 1-2; Figs 9A, 11B). Mesial denticles significantly smaller than distal denticles is a condition typically seen in juvenile theropods like Majungasaurus and tyrannosaurids and was said to enhance the piercing function of the tooth (Carr & Williamson, 2004; Fanti & Therrien, 2007; Fowler et al., 2011; Hendrickx et al., 2019). Dental evolution in megalosaurids is strongly dependent on the relationships of Spinosauridae (see next section). The dentition of Megalosauridae, characterised by a mesial carina facing mesiolabially in mesial teeth, centrally positioned carinae on both mesial and lateral crowns, a mesial carina terminating above the cervix, and short to well-developed interdenticular sulci between distal denticles (Hendrickx et al., 2015b), is diagnosed by a dentary with 10 to 14 tooth positions (char. 7:1) and a crown skull ratio ranging from 7 to 9 (char. 22:2; i.e., relatively large maxillary teeth compared to skull length; Tree 1; Fig. 9A) when it forms the sister clade of Monolophosaurus + Spinosauridae (Trees 1, 5-6; Fig. 9A). The presence of particularly large denticles (≤ 8 de/5mm; char. 34:3) additionally supports Megalosauridae when it only includes Torvosaurus, Megalosaurus, and Wiehenvenator and is sister to Spinosauridae (Tree 2; Fig. 9B). However, a mesial carina restricted to the apical part of the crown (char. 32:0) is the only apomorphic dental feature supporting Megalosauridae when sister to the clade Wiehenvenator + Cretaceous Spinosauridae (Tree 4; see supporting information).

Minor dental features related to the denticle morphology and crown ornamentations characterizes the different subclades classified within Megalosauridae or at the base of Megalosauroidea. The clade Eustreptospondylus + Dubreuillosaurus is for instance supported by the presence of subquadrangular distal denticles in lateral teeth (char. 38:1; Tree 2; Fig. 9B) and the absence of transverse undulations (char. 43:0; Trees 1, 5-6; Fig. 9A) whereas Megalosaurinae, the clade gathering Megalosaurus and Torvosaurus and only recovered in one topology (Tree 4), is characterised by particularly large distal denticles (≤ 8 de/5mm; char. 34:3) and well-developed interdenticular sulci (char. 40:2; Tree 6). With four to five dental autapomorphies, Torvosaurus has a particularly diagnostic dentition among non-spinosaurid megalosauroids made of three premaxillary teeth (char. 5:0), extremely tall and particularly elongated (CHR > 2.5; char. 24:2) maxillary crowns of more than 9 cm (char. 20:4) compared to the skull length (crown skull ratio of more than 9; char. 22:3). The combination of these dental features is directly associated with the particularly large size (>10m in body length) and hypercarnivory of this apex predator from the Late Jurassic of the United States and Europe (Britt, 1991; Hendrickx & Mateus, 2014b; Rauhut et al., 2020).

Similar to Hendrickx et al.’s (2019) results, the most important dental transition observed in the evolution of nc theropods (and probably the whole theropod clade) occured during the radiation of Spinosauridae (Figs 9-10). The latter here refers to the group encompassing Cretaceous forms with crocodile-like skulls and typically classified into the subfamily level clades Spinosaurinae and Baryonychinae (Sereno et al., 1998; Malafaia et al., 2020; Barker et al., 2021; Schade et al., 2023). Some recent studies, however, recovered Spinosauridae as a clade encompassing these Cretaceous forms as well as an early branching megalosauroid from the Jurassic with a typical tetanuran skull morphology namely, Wiehenvenator for Cau (2024; Trees 3-4; Fig. 10) and Monolophosaurus for Schade et al. (2023) and Kellerman et al. (2025; Trees 1, 5-6; Fig. 9A). In these phylogenies, Spinosauridae sensu Hendrickx et al. (2015a) is diagnosed by zero (Tree 4; Cau, 2024 SCT; Spinosauridae = Wiehenvenator + Cretaceous spinosaurids), one (Trees 1, 5-6; Fig. 9A), or three synapomorphies (Cau, 2024; OSP; Tree 3: Wiehenvenator + Scipionyx + Cretaceous spinosaurids; Fig. 10) namely, the loss of interdenticular sulci (Tree 1), a subcircular cross-section outline in mesial teeth (char. 19:0), rather small distal denticles, with a distal denticle density ranging from 16 to 29 denticles per 5 mm (char. 34:1), and subquadrangular distal denticles (char. 38:1; Tree 3). In the latter evolutionary hypothesis where Cretaceous spinosaurids evolved from megalosaurine-like theropod such as Wiehenvenator, a reduction in denticle size, coupled with the emergence of a subcircular cross-sectional outline in mesial teeth, appears to represent the initial evolutionary modifications leading to the highly derived and fully specialised dentition of Cretaceous spinosaurids.

The numerous dental apomorphies observed in Cretaceous spinosaurids reflect their extensive cranial and dental adaptations to a highly specialised diet composed primarily but not exclusively, of fish (Charig & Milner, 1997; Buffetaut et al., 2004; Dal Sasso et al., 2005; Hendrickx et al., 2016, 2019). This specialised feeding ecology parallels the ecological shift undergone by spinosaurids, from fully terrestrial theropods to semi-aquatic predators (Amiot et al., 2010; Ibrahim et al. 2014, 2020a). The radiation of spinosaurid theropods was accompanied by a surprisingly large number of dental changes, namely an increase in the number of premaxillary tooth positions from four to seven teeth (char 5:4), the transition from a (size-related/allometric) homodont to strongly heterodont premaxillary and mesial maxillary dentition (chars 8:3 and 9:3), the enlargement of mesial dentary teeth (char 10:1), the change from a pseudoheterodont ziphodont dentition to a morphologically homodont conidont dental morphology (chars 12:1 and 13:1), the anterior projection (i.e., procumbency) of mesialmost maxillary teeth (char 16:2), the development of a subcircular cross-section outline at the base-crown in mesial teeth (char 19:0), the decrease in the labiolingual compression of lateral teeth (char 23:2), as well as the development of flutes (chars 41:3) and marginal undulations in both mesial and distal dentitions (char. 43:2). Based on their larger dentition-based datamatrix of 145 characters, Hendrickx et al. (2019) listed additional dental modifications in Cretaceous spinosaurids such as the displacement of the premaxillary tooth row anterior to the external naris, the mediolateral constriction of the upper tooth row at the transition between the premaxillary and maxillary dentition and giving a terminal rosette to the anterior tip of the snout in palatal view, the development of a similar terminal rosette in the anterior mandible, the basal extension of both mesial and distal carinae to reach the root in mesial and lateral crowns, the acquisition of flutes on the labial and lingual surfaces of the lateral crowns, the development of straight crowns with a convex distal margin, and strongly apically tapered roots with a subcircular cross-section. Dental adaptation towards a piscivorous diet exacerbated in Spinosaurinae during the middle Cretaceous with the acquisition of the following apomorphic dental characters typically restricted to this clade (at least among nc theropods): the development of widely spaced maxillary teeth, with wide gaps between them (char. 18:5), a decrease in tooth compression so that the most compressed teeth are incrassate and subcircular in cross-section (char. 23:3), the loss of the distal curvature of the crowns (char. 27:2), as well as mesial and distal denticles in both mesial and distal dentitions (char. 30:5; char. 31:5). The early dental evolution of spinosaurids, along with the evolution of the dentition in Baryonychinae and Spinosaurinae, was comprehensively addressed by many authors (Sereno et al., 1998; Buffetaut, 2011; Serrano-Martínez et al., 2016; Vullo et al., 2016; Sales & Schultz, 2017; Hendrickx et al., 2019; Heckeberg & Rauhut, 2020; Lacerda et al., 2022; D’Amore et al., 2024; Sereno et al., 2026), and will therefore not be reiterated here.

Allosauroidea

With or without piatnitzkysaurids, the major dental change (i.e., seven dental apomorphies) obtained for Allosauroidea by Hendrickx et al. (2019) is not recovered in this study. Instead, allosauroids are only diagnosed by one to two dental synapomorphies namely, lateral crowns with well-developed interdenticular sulci (char. 40: 2) when piatnitzkysaurids are included within allosauroids (Tree 2; Fig. 11B), and strongly compressed (CBR ≤ 0.4) lateral crowns (char. 23:0; Trees 1, 3-4; Figs 11A, 12) with subquadrangular mesial denticles (char. 37: 1; Trees 1, 5-6; Fig. 11A) when they are outside of Allosauroidea. This result is explained by the fact that this study considers a larger sample of allosauroid and tyrannosauroid taxa and a lower number of characters applied to a wider range of dentition-based features. Even though the dental anatomy of allosauroids is relatively well-known, with many early branching forms preserving a complete or relatively complete dentition (e.g., Acrocanthosaurus, Allosaurus, Asfaltovenator, Sinraptor, Yuanmouraptor, Yangchuanosaurus), results of this study shows that the dental anatomy of allosauroids remained relatively unchanged throughout their evolution, with the most important dental changes occurring during the radiation of some metriacanthosaurids and carcharodontosaurines. Two to three dental synapomorphies indeed constrain the clade gathering Sinraptor and the two Yangchuanosaurus species: the development of a labial depression restricted to the crown base in lateral teeth (char. 26:1; Trees 1-2, 5-6; Fig. 11) and poorly distally recurved lateral crowns (char. 27:1; Trees 1-6) as well as relatively tall maxillary crowns of 6 to 9 cm in height (char. 20:3; Trees 3-4; Fig. 12) and an irregular enamel surface texture (char. 44:0; Tree 2; Fig. 11B) in a few topologies. This list of dental apomorphies defining the clade Sinraptor + Yangchuanosaurus should, however, be seen as tentative as the present analysis does not include the recently described Alpkarakush kyrgyzicus, a member of the group possibly characterised by an unusual mesial dentition (see below). Additionally, the phylogenetic position of Yangchuanosaurus hepingensis, referred to as Sinraptor hepingensis by some authors like (e.g., Zou et al., 2025), remains uncertain within this clade. If no dental feature diagnoses Metriacanthosauridae, which likely results from the disparate dental morphology displayed by metriacanthosaurids and the poorly known dentition of the basally branching carcharodontosaurians Neovenator and Concavenator, the recently described Yuanmouraptor (Zou et al., 2025) shows a particularly diagnostic dentition made of five synapomorphies: a dentary with 10 to 14 tooth positions (char. 7:1), a mesial carina restricted to the apical part of the crown (char. 32:0), a denticle crown ratio (DCR) between 1 and 2 (char. 35:2), mesial denticles significantly smaller than distal ones (DSDI>1.2; char. 36:2/3), and fluted mesial and lateral teeth (Fig. 11A). Yuanmouraptor is in fact the only allosauroid to bear fluted mesial and lateral teeth, and the second among non-avian avetheropods after Austroraptor (Novas et al., 2009; Hendrickx et al., 2019; Motta & Novas, 2025). Nevertheless, an isolated mesial crown bearing numerous flutes on both labial and lingual sides (IGB 2-6) and tentatively referred to a second metriacanthosaurid, Alpkarakush kyrgyzicus, by Rauhut et al. (2024) suggests that several Middle Jurassic metriacanthosaurids from Asia may have convergently developed fluted teeth probably well before ceratosaurids and spinosaurids. As previously mentioned, fluted teeth are typically present in piscivorous animals such as spinosaurids and marine reptiles (Hendrickx et al., 2019), suggesting that Yuanmouraptor and Alpkarakush may have been piscivorous metriacanthosaurids. The lateral dentition of both Yuanmouraptor and Alpkarakush, however, shows the typical ziphodont morphology seen in other allosauroids: the lateral teeth are labiolingually compressed, strongly distally recurved, and have denticulated carinae (Rauhut et al., 2024). In fact, a higher DCR suggests that the denticles of Yuanmouraptor were getting larger relative to the crown rather than reducing in size, unlike those of piscivorous theropods (e.g., baryonychines; Charig & Milner 1997). This suggests that, in contrast to spinosaurids, the main function of the fluted dentition of Yuanmouraptor and Alpkarakush was probably not to impale slippery aquatic prey such as fish. Hendrickx et al. (2020a) argued that the dentition of Sinraptor and other closely related allosauroids such as Allosaurus showed adaptations towards a predatory lifestyle, including premaxillary teeth capable of enduring tooth-to-bone contact and crowns with widely separated mesial and distal carinae capable of inflicting widely open wounds. The lateral dentition of Allosaurus was in fact pachydont and direct evidence shows that this theropod had bone-crunching bites, as revealed by the discovery of a Stegosaurus cervical plate with a bite pattern matching that of Allosaurus (Carpenter et al., 2005; Hone & Rauhut, 2010; Hendrickx et al., 2019; Lei et al., 2023). It is, therefore, plausible that the fluted and strongly recurved lateral teeth of the presumably predatory Yuanmouraptor and Alpkarakush contributed to stabilizing a lethal bite as they pierced through a prey’s body. However, this hypothesis requires further support from additional evidence, particularly concerning the functional morphology of the skull, neck, and forelimb in these poorly known metriacanthosaurids.

Whether or not megaraptorans are included in Allosauria (= Allosaurus + Carcharodontosauria), dental evolution in this clade was characterised by an increase in the number of maxillary teeth, reaching 15 to 17 tooth positions (char. 6:2; Tree 2-3; Figs 11B, 12A). However, Allosauria is not recovered when Asfaltovenator is included, with this taxon being either placed within Allosauridae, the earliest diverging allosauroid clade, or as an early branching allosauroid slightly more derived than Allosaurus. In both cases, no dental synapomorphy diagnoses Allosauridae and the clade Asfaltovenator + more derived allosauroids. Interestingly, both taxa show several dental apomorphies, namely 10 to 14 dentary teeth (char. 7:1), a subcircular or lanceolate cross-sectional outline of mesial teeth at crown base (char. 19:0/1), and a mesial dentition with mesial denticles significantly smaller than distal ones (DSDI>1.2; char. 36:1/3) in Asfaltovenator, and five premaxillary teeth (char. 5:2), 15 to 17 maxillary teeth (char. 6:2), and the presence of the tallest crowns in the middle part of the maxilla in Allosaurus (char. 21:1) (Gilmore, 1920; Madsen, 1976; Rauhut & Pol, 2019) (Tree 1; Fig. 11A). Unlike megalosaurids but similar to spinosaurids, variation in the number of premaxillary, maxillary, and dentary teeth was relatively important within Allosauroidea: Allosaurus and Neovenator had five premaxillary teeth when all other allosauroids retained the plesiomorphic premaxillary tooth count of four; Asfaltovenator, carcharodontosaurines, and most metriacanthosaurids had 13 to 14 maxillary teeth whereas Allosaurus and non-carcharodontosaurine carcharodontosaurians had 15 to 17; and Asfaltovenator and Yuanmouraptor had 14 dentary teeth while other allosauroids had a mandible with 15 to 19 tooth positions (Table 1).

Although no dental synapomorphy consistently defines the clade Carcharodontosauria (Neovenator + Carcharodontosauridae) across most topologies, the presence of transverse and pronounced marginal undulations on the lateral crowns (char. 43:4), a feature well known to typify carcharodontosaurid teeth (Sereno et al., 1998; Coria & Currie 2006; Brusatte et al., 2007; Hendrickx et al., 2019), serves to diagnose Carcharodontosauridae when Concavenator is excluded from the clade (Trees 1 and 6; Fig. 11A), or carcharodontosaurids more derived than Concavenator when the latter occupies the earliest branching position within the group (Trees 2-4; Figs 11B, 12). The presence of tall maxillary teeth exceeding 6 cm further supports Carcharodontosauridae when ‘Eocarcharia’ is placed outside this clade (Tree 6). However, MNN GAD7, a maxilla attributed to ‘Eocarcharia’ by Sereno & Brusatte (2008), was recovered within Carcharodontosauridae by Kellerman et al. (2025) and Cau & Paterna (2025), suggesting that the isolated teeth referred to ‘Eocarcharia’, which share a similar morphology with the single unerupted maxillary tooth of MNN GAD7, most likely belong to carcharodontosaurids. The in-situ maxillary tooth of MNN GAD7 and isolated teeth referred to ‘Eocarcharia’ all exhibit crown heights under 6 cm; however, it remains possible that larger maxillary teeth were present in other African carcharodontosaurids from the Lower Cretaceous. If so, the presence of maxillary teeth exceeding 6 cm could also serve as a diagnostic feature of Carcharodontosauridae.

As noted earlier, the most significant dental transformations in the evolution of Carcharodontosauridae took place with the emergence of Carcharodontosaurinae, whose dentition exhibits two to four synapomorphies: a decrease in the number of maxillary tooth positions to less than 15 (char. 6:1), lateral crowns of more than 6 cm in height (char. 20:3) and strongly flattened (CBR ≤ 0.4; char. 23:0) in Trees 1 and 3-4 (Figs 11A, 12) as well as a weak mesiodistal constriction between crown and root in a few lateral teeth (char. 25:2), slightly distally recurved lateral teeth (char. 27:1), and particularly large denticles (≤ 8 de/5mm; char. 34:3) in Tree 2 (Fig. 11B). Unlike allosaurids and metriacanthosaurids, the lateral dentition of these gigantic theropods (>10 m in length; Coria & Salgado, 1995; Sereno et al., 1996; Calvo & Coria, 1998; Canale et al., 2022) included particularly labiolingually compressed and poorly recurved maxillary crowns which appear to be much better suited for cutting through flesh than bones. The feeding ecology of Carcharodontosaurinae is particularly poorly known and currently revealed through biomechanical analyses (Mazzetta et al., 2004; Therrien et al., 2005; Rayfield, 2011; Sakamoto, 2022; Rowe & Rayfield, 2025). Using biomechanical model of the mandible, Therrien et al. (2005) found that Giganotosaurus had a powerful slicing bites and was interpreted as a generalised predator feeding on a wide spectrum of prey items. Sakamoto (2022), however, noted that, although sharing the same size as Tyrannosaurus, Carcharodontosaurus had a much lower bite force than the former. Based on dental morphology, it is here postulated that at least some carcharodontosaurines such as Carcharodontosaurus may have favoured a scavenger feeding ecology, using their relatively powerful bites but particularly flattened and poorly recurved maxillary teeth showing a weak mesiodistal compression at the cervix and large denticles to carefully remove large chunk of flesh from carcasses such as those of the particularly huge coeval sauropods (e.g., Paralititan).

Dental evolution and feeding ecologies in nc theropods

The wide range of dentition and crown morphologies in nc theropods reflects an underappreciated diversity of dietary habits in an early branching group of dinosaurs that includes forms ranging from small taxa of less than one metre (Berthasaura; de Souza et al. 2021) to giants exceeding 12 metres (e.g., Spinosaurus, Giganotosaurus; Dal Sasso et al., 2005; Therrien & Henderson, 2007; Ibrahim et al., 2014; Canale et al., 2022; Henderson, 2023; Fig. 13). Although theropods almost certainly originated from faunivorous dinosaurs possessing a ziphodont dentition likely exhibiting a subnarial gap and made of distally denticulated mesial crowns as well as distally recurved 1–3 cm tall crowns with denticulated mesial and distal carinae (Cabreira et al., 2016; Müller et al., 2018; Hendrickx et al., 2019; Ballell et al., 2022), the presence or absence of several dental features in the earliest-diverging theropods remain uncertain. The dentition of several saurischians closely related to theropods such as the earliest branching sauropodomorphs Buriolestes and Eoraptor (Sereno et al. 2013; Müller et al. 2018; Moro et al. 2024) and the possible herrerasaur Daemonosaurus (Nesbitt & Sues, 2020; Novas et al., 2021; Martínez et al., 2025) for instance suggests that the first theropods may have possessed both ziphodont and folidont lateral teeth. Likewise, the dental morphology of Daemonosaurus and Tawa reveals that early branching theropods may have also bore fluted teeth (Hendrickx et al., 2019; Nesbitt & Sues, 2020). The earliest theropods seemed to have shared the general body shape and feeding ecology of their saurischian ancestors (Fig. 13). Similar to Buriolestes, the first theropods from the Carnian were gracile long snouted bipedal carnivores using their elongated neck, long forearms with three functional fingers ended by sharp and strongly recurved claws, and ziphodont dentition with both retrocumbent premaxillary and procumbent mesial maxillary and dentary teeth to feed opportunistically on a wide variety of small prey items (Nesbitt et al., 2009; Martínez et al., 2011, 2025; Cabreira et al., 2016; Müller et al., 2018; Novas et al., 2021; Moro et al., 2024; Fig. 13). Pending on the position of Eodromaeus and Tawa, they may have only differed from their saurischian ancestors by their larger mesial dentary dentition (which conversely evolved in neotheropods if Eodromaeus and/or Tawa are early branching theropods). Coelophysoids, representing the first theropod radiation from to the Late Triassic and Early Jurassic, retained this general morphology and feeding ecology, becoming only larger and slenderer, and likely increasing the number of premaxillary, maxillary, and dentary teeth if they descended from Tawa-like theropods (Fig. 13).

Fig. 13 A diagram illustrating the feeding ecologies, major dental shifts, and body size through time in non-avian saurischian theropods.

During the Norian, some non-coelophysoid theropods (e.g., Liliensternus, Zupaysaurus) underwent a notable increase in body size exceeding four metres in length, accompanied by a shortening of the cranium and upper dentition so that the upper tooth row ends at the level of the lachrymal. This shift was associated with a transition toward preying on larger animals and, by the Early Jurassic, the evolution of jaws bearing fewer teeth (<15 maxillary and <18 dentary teeth) and taller crowns (>3cm) with proportionally larger denticles (<15 de/5mm), as seen in neotheropods such as Sinosaurus and Dilophosaurus. An increase in body size and crown height continued in neotheropods and averostrans throughout the Early and Middle Jurassic, with megapredators of more than six metres bearing ziphodont lateral crowns of more than four cm evolving in ceratosaurs (Saltriovenator, MPEF-PV 6775), megalosauroids (Monolophosaurus, Megalosaurus, Afrovenator), allosauroids (Asfaltovenator, Yuanmouraptor, Alpkarakush), and probably already in derived non-averostran neotheropods such as Cryolophosaurus. This trend was accompanied by the development of a fully decumbent dentition (i.e., the loss of retrocumbent and procumbent teeth) and, in tetanurans, the anterior displacement of the distal end of the upper tooth row, with the distalmost maxillary tooth aligned with the antorbital fenestra (Fig. 13). If the majority of basally branching neotheropods (e.g., dilophosaurids, piatnitzkysaurids, megalosaurids, allosaurids) retained the ziphodont crowns with superficial ornamentations (transverse and marginal undulations, interdenticular sulci, etc.) of their ancestors, the first important changes in the ziphodont dental morphology occured by the late Early-Middle Jurassic, with the development of fluted teeth in metriacanthosaurids (Yuanmouraptor, Alpkarakush; Hendrickx et al., 2019; Rauhut et al., 2024), poorly recurved lateral crowns with a straight distal profile in metriacanthosaurids and piatnitzkysaurids, and crowns with apically hooked distal denticles, a strongly twisted mesial carina, and a size discrepancy between mesial and distal denticles in piatnitzkysaurids (Hendrickx et al., 2019). Dental diversity in ziphodont theropods continued during the Late Jurassic with the evolution of elongated and proportionally tall maxillary crowns in ceratosaurids (Ceratosaurus), extremely tall crowns (>10 cm) with large denticles (<6 de/5mm) in megalosaurids (Torvosaurus), and a pachydont dentition in allosaurids (Allosaurus; Hendrickx et al., 2019, 2020a). Each of these clades also evolved different mesial crown morphologies i.e., conical and fluted, with a strongly labially displaced distal carina in ceratosaurids, elongated and subsymmetrical in megalosaurids, and incisiform, with lingually displaced mesial and distal carinae in allosaurids (Henderson, 1998; Madsen & Welles, 2000; Bakker & Bir, 2004; Hendrickx et al., 2015b, 2020a). The best-known representatives of these clades, Ceratosaurus, Torvosaurus, and Allosaurus, were contemporaneous apex predators that inhabited what are now North America and the Iberian Peninsula during the Kimmeridgian–Tithonian (Gilmore, 1920; Britt, 1991; Mateus et al., 2006; Hendrickx & Mateus, 2014b; Malafaia et al., 2015; Foster, 2020). Their distinct dental morphologies indicate differing feeding strategies and/or the occupation of separate trophic niches, with Ceratosaurus possibly preying on more aquatic animals (see section “Ceratosauria”), whereas Torvosaurus and Allosaurus likely targeted the herbivorous dinosaurs that were particularly abundant in these ecosystems at the time (e.g., Henderson, 1998; Rayfield et al., 2001; Bakker & Bir, 2004; Carpenter et al., 2005; Hone & Rauhut, 2010; Pahl & Ruedas, 2023; Lei et al., 2023).

Our current understanding of theropod relationships suggests that, by the Middle Jurassic (and possibly as early as the Early Jurassic, should the provenance of the putative therizinosaur Eshanosaurus from the Hettangian Lufeng Formation of China be confirmed; Xu et al., 2001; Barrett, 2009), averostrans underwent a rapid diversification in both morphology and ecology, with two, possibly three lineages, i.e., ceratosaurs, “chilesaurs”, and maniraptoriforms, convergently expanding into ecological niches traditionally occupied by herbivorous non-theropod dinosaurs (Xu et al., 2009; Zanno & Makovicky, 2011; Novas et al., 2015; Wang et al., 2019; Tschopp et al., 2020; Fig. 13). The stratigraphic record of the two herbivorous nc theropods from the Jurassic, Limusaurus and Chilesaurus, is restricted to the Late Jurassic (Oxfordian and Tithonian, respectively); however, their phylogenetic position at the base of the ceratosaur and tetanuran clades, respectively, in some phylogenetic studies (Novas et al., 2015; Chimento, 2018; Cau, 2024; Hendrickx et al., 2024; Cau & Paterna, 2025) suggests that the lineages of herbivorous/omnivorous theropods they represent likely originated in the Early or Middle Jurassic (Novas et al., 2015; Wang et al., 2017a; Chimento, 2018; Cau, 2024; Fig. 13). This ecological radiation was coupled by a drastic change in dental morphology, which in nc theropods was characterised by the reduction of the number of tooth positions, a simplification of the crowns (i.e., no carinae, denticles, nor crown ornamentations; Gianechini et al., 2011; Zanno & Makovicky, 2011; Hendrickx et al., 2019) and, in Chilesaurus, the development of procumbent teeth with a constriction between root and crown (Fig. 13). This dental trend ultimately led to the total loss of teeth independently in one or two ceratosaur lineages (i.e., Elaphrosaurinae and Berthasauridae; Wang et al., 2017a, b, 2020; de Souza et al., 2021; Hendrickx et al., 2024) and numerous maniraptoriform clades (e.g., Ornithomimosauroidea, Caenagnathoidea, Enantiornithes, Neornithes; Zanno & Makovicky, 2011; Louchart & Viriot, 2011; Hendrickx et al., 2019; Wang et al., 2020). Ontogenetic edentulism in Limusaurus reveals that, in elaphrosaurine and possibly in the lineage leading to Berthasaura, tooth loss began anteriorly in the premaxilla and dentary, and posteriorly in the maxilla, then anteriorly and posteriorly in the maxilla and dentary (Wang et al., 2020; Fig. 13). The loss of teeth in these ceratosaurs was accompanied by the progressive development of a keratinised rhamphotheca, which initially formed over the anteriormost regions of the cranium and mandibles where teeth were first lost, then extended to areas of the jaws where teeth had become functionally reduced, and ultimately covered the entire edentulous region following a complete or nearly complete remodeling of the teeth (Louchart & Viriot, 2011; Wang et al., 2017a, b, 2020; Aguilar-Pedrayes et al., 2024).

An increased consumption of fish and a gradual adaptation towards a predominantly piscivorous diet marked the onset of the second major shift in dental morphology among nc theropods. This trend likely started in the Middle or Late Jurassic with the emergence of spinosaurids (here referred to the clade including baryonychines and spinosaurines) from megalosaur- or megalosaurid-like taxa closely related to Monolophosaurus, Magnosaurus, Megalosaurus, or Wiehenvenator (n.b., some of these taxa are even recovered among Spinosauridae in some cladistic analyses; Figs 9-10). Stomach contents (Eudes-Deslongchamps, 1837; Allain, 2005) and trackways (Razzolini et al., 2016) reveal that Middle Jurassic megalosauroids, which favoured nearshore environments (Rauhut et al., 2016), were most likely at least occasional fish eaters, supporting the idea that spinosaurids evolved from theropods that were already piscivorous (Allain, 2005; Razzolini et al., 2016). However, unlike other carnosaurs, spinosaurids became semi-aquatic and evolved numerous cranial, postcranial, and dental adaptations that facilitated the capture of aquatic prey items (Charig & Milner, 1997; Amiot et al., 2010; Ibrahim et al., 2014; Hendrickx et al., 2016; Hone & Holtz, 2017; Sales & Schultz, 2017; Ibrahim et al., 2020a; Hone & Holtz, 2021; Sereno et al., 2022, 2026; Smart & Sakamoto, 2024). Baryonychinae, the first radiation of spinosaurid currently known from the Barremian–Albian, evolved narrow and elongated skulls, retracted nares, conidont fluted teeth with minute denticles and a veined enamel surface texture, undulated jaws with a large number of teeth (>5 premaxillary, >20 maxillary, and >25 dentary tooth positions) and spatulated anterior extremities (“rosette”), procumbent mesial maxillary teeth, morphologically homodont but allometrically heterodont dentition with enlarged mesial maxillary and dentary teeth, as well as robust forelimbs with enlarged and strongly recurved manual ungual I (Charig & Milner, 1997; Sereno et al., 1998, 2026; Rayfield et al., 2007; Barker et al., 2021; Mateus & Estraviz-López, 2022; Lacerda et al., 2022; D’Amore et al., 2024). Such evolution towards a predominantly piscivorous feeding ecology and a diet involving larger prey items continued in spinosaurines during the “Mid”-Cretaceous (Aptian–Cenomanian) with jaws bearing a reduced number (12 maxillary and 15 dentary teeth) of larger, straighter, conical (i.e., with a subcircular cross-section and a convex distal profile), unserrated, and strongly fluted crowns, widely spaced maxillary teeth, and strongly retracted nares (Dal Sasso et al., 2005; Kellner et al., 2011; Ibrahim et al., 2014; Hendrickx et al., 2016; Sales & Schultz, 2017; Hone & Holtz, 2021; Schade et al., 2023; Sereno et al., 2026). Although they likely consumed more aquatic prey items than their ancestors, multiple lines of direct and indirect evidence, including stomach contents, a broken tooth embedded in a vertebra, snout morphology, isotopic signature, and taphonomic association, indicate that both baryonychines and spinosaurines were not strictly piscivorous. Instead, they were generalist carnivores that also preyed on terrestrial animals such as pterosaurs, juvenile iguanodontids, and possibly sauropods (Charig & Milner, 1997; Buffetaut & Suteethorn, 1999; Buffetaut et al., 2004; Sales et al., 2016; Vullo et al., 2016; Hone & Holtz, 2017, 2021; Hassler et al., 2018; D’Amore et al., 2024).

Dental evolution in another clade of nc theropods from the Cretaceous, noasaurid ceratosaurs (here referred to non-elaphrosaurine noasaurids, or noasaurines in some classifications; see Hendrickx et al., 2024), may have also been influenced by an increase in the consumption of fish. Similar to spinosaurids, noasaurids convergently evolved enlarged and strongly procumbent mesial fluted teeth with reduced denticles, labiolingually thick fluted lateral teeth (Masiakasaurus; Sampson et al., 2001; Carrano et al., 2002, 2011; Hendrickx et al., 2024), and enlarged and strongly recurved manual unguals I (Noasaurus; Bonaparte & Powell, 1980; Agnolín & Chiarelli, 2010; Hendrickx et al., 2024), a combination of derived features interpreted as possible adaptations to a piscivorous diet (Carrano et al., 2002; Hendrickx et al., 2024). The dentition of noasaurids, however, differed markedly from that of spinosaurids. Most of their lateral teeth retained the plesiomorphic ziphodont condition and exhibited comparatively large denticles whereas the mesialmost crowns were folidont, i.e., they showed an important constriction between crown and root, with carinae arranged mesiodistally. Additionally, the maxillary teeth were small, homodont, and decumbent (Carrano et al., 2002; Fanti & Therrien, 2007; Lindoso et al., 2012; Hendrickx et al., 2019, 2024). Although noasaurids may not have been predominantly piscivorous like spinosaurids, these opportunistic mesopredators inhabiting coastal and fluvial environments evolved a dentition well suited for prehension, allowing them to grasp small, whole prey items such as fish, and likely also lizards and various invertebrates (Sampson et al., 2001; Carrano et al., 2002; Hendrickx et al., 2024).

Throughout their evolutionary history in the Cretaceous, non-elaphrosaurine noasaurids remained small-bodied opportunistic mesopredators and thus did not compete with their larger abelisaurid relatives that coexisted with them across most Gondwana during the Cretaceous and took the role of apex predators (Pereyra et al., 2025b, a; Fig. 13). Pereyra et al. (2025b) recently demonstrated that a specialised predatory strategy had already evolved in Early Cretaceous abelisaurids like Spectrovenator so that their dental evolution, characterised by a posterior shift of the tallest maxillary crowns toward the mid-maxilla, reduced variation in crown size along the maxilla, a decrease in the size of the mesialmost dentary teeth, and an increase in dentary tooth count, likely reflects adaptation to this specialised hunting ecology. Late Cretaceous abelisaurids, however, developed diverse snout and dental morphologies indicative of differing hunting strategies. While some forms from the latest Cretaceous of Europe (e.g., Arcovenator) developed a lateral dentition reminiscent to that of piatnitzkysaurids in their tall and strongly distally recurved crowns with a distal carina markedly deflected labially and a mesial carina bearing comparatively small denticles and not extending to the root, other from Gondwana (e.g., Majungasaurus, Carnotaurus) conversely evolved a brachydont dentition with thick mesial teeth and subsymmetrical and poorly recurved lateral crowns adapted to a bite-and-hold predatory and ambush attack strategy (Therrien et al., 2005; Sampson & Witmer, 2007; Delcourt, 2018; Meso et al., 2021a; Hendrickx et al., 2025).

In the early and mid-Cretaceous, the role of apex terrestrial predators was also played by another clade of nc theropods, carcharodontosaurians (Neovenator + carcharodontosaurids), that may have compete with abelisaurids at the top of the food chain in some Gondwanan ecosystems of South America and Africa (Novas et al., 2013; Ezcurra & Novas, 2016; Ibrahim et al., 2020b). Carcharodontosaurians evolved from large-bodied Middle or Late Jurassic allosauroids that already possessed a similar ziphodont dentition characterised by relatively tall (> 4cm), distally recurved, denticulated crowns, as well as close cranial and postcranial anatomies, suggesting broadly analogous feeding ecologies (Therrien et al., 2005; Snively & Russell, 2007; Rauhut, 2011; Nabavizadeh & Weishampel, 2023). The development of slightly distally recurved lateral crowns with marked marginal undulations in early branching carcharodontosaurids, together with the reduced number (<15) of maxillary tooth positions and the tall (>6 cm), strongly compressed (CBR ≤ 0.4) lateral crowns, some displaying a constriction between crown and root, with large (≤ 8de/5mm) denticles in carcharodontosaurines, however, indicates a shift toward a somewhat different faunivorous feeding strategy relative to their ancestors. Although the enlargement of crowns and denticles in carcharodontosaurids reflects the overall increase in skull and body size seen throughout their evolution, the derived dentition of carcharodontosaurines, exemplified by Carcharodontosaurus with its particularly flattened, slightly constricted crowns featuring extremely pronounced marginal undulations and mesiodistally broad apices showing a convex distal profile, indicates the evolution of a more specialised carnivorous feeding ecology. This may have included greater reliance on scavenging and processing the carcasses of gigantic titanosaurs that were particularly abundant during the mid-Cretaceous. In contrast to abelisaurids, which survived until the end of the Cretaceous, and likely similar to spinosaurids (but see Olmedo-Romaña et al., 2025 for a different opinion), carcharodontosaurids went extinct during a faunal turnover that took place around the early–middle Turonian (Novas et al., 2005, 2013; Ezcurra & Novas, 2016; Delcourt & Grillo, 2018; Delcourt et al., 2020; Meso et al., 2021b; Canale et al., 2022; Morrison et al., 2025). The extinction of these two nc theropod lineages containing gigantic forms, which enabled other theropods like abelisaurids, megaraptorans, and unenlagiines to thrive and dominate the role of apex predators, may have resulted from their highly specialised feeding ecologies, which left them unable to withstand the major faunal and climatic shifts that occurred during the Turonian (Candeiro et al., 2017a; Aranciaga Rolando et al., 2022; Morrison et al., 2025).