Ginsu Shark

Cretoxyrhina mantelli inhabited the Western Interior Seaway, a vast epicontinental waterway dividing North America from the Gulf of Mexico to the Hudson Strait during the Late Cretaceous, 100 to 72 million years ago. The water was slightly less saline than the open ocean, with subtropical to temperate temperatures. The sea had variable depth, with shallow areas rich in life and deeper zones with low bottom oxygen. Beyond North America, C. mantelli was cosmopolitan, occurring in the European Tethys Sea and possibly other tropical ocean regions.

Cretoxyrhina mantelli was an active apex predator that attacked the largest available prey in the Western Interior Seaway. Bite mark evidence documents predation on several-meter mosasaurs, plesiosaurs, the giant fish Xiphactinus, sea turtles such as Protostega and Archelon, and pterosaurs like Pteranodon. The smooth, non-serrated teeth, similar to those of the mako shark, were adapted to pierce and hold actively struggling prey, not to saw like a great white shark. The attack mechanism likely involved high speed and multiple bites.

The body morphology of Cretoxyrhina mantelli, close to the modern mako shark, suggests it was a high-speed swimmer capable of burst speeds to capture agile prey. The ability to attack pterosaurs resting on the sea surface (documented by Hone et al. 2018) indicates opportunistic and versatile behavior. There is no evidence of social behavior, and the species was probably solitary. Production of offspring through ovoviviparity, as in most lamniformes, is likely but not directly confirmed in the fossil record.

Cretoxyrhina mantelli had a cartilaginous skeleton with densely calcified vertebrae, allowing growth ring analysis. Comparison with the modern mako shark suggests elevated metabolism for a chondrichthyan, possibly with some degree of regional endothermy as in the mako and great white shark. The estimated asymptotic length of 6.91 m and birth at 1.28 m suggest a relatively rapid growth rate. Placoid scales, preserved in at least one specimen, were of the smooth lisoric type, suitable for turbulence reduction during fast swimming.

Original description of Cretoxyrhina mantelli by Swiss naturalist Louis Agassiz, based on fossil teeth from the Cretaceous chalk of England, named in honor of geologist Gideon Mantell. Agassiz, in his monumental work on fossil fish, characterizes C. mantelli teeth as smooth, without serration on cutting edges, with a distinct bifurcated root and shiny enamel. The size of the teeth, which can exceed 5 cm in height, already indicates a large animal. The originally described species was later recognized as also occurring in the Western Interior Seaway of North America, where the best specimens would be found more than a century later. This work is the mandatory nomenclatural starting point for all literature on C. mantelli.

Fossil tooth of Cretoxyrhina mantelli from the Niobrara Formation, Gove County, Kansas, USA. The smooth teeth without serration on the edges are the diagnostic feature described by Agassiz (1843).

Dental reconstruction of Cretoxyrhina mantelli based on Bourdon and Everhart (2011) and Shimada (1997). The teeth show the homogeneous non-serrated pattern described by Agassiz (1843).

Detailed analysis of the dentition of Cretoxyrhina mantelli from the Niobrara Chalk of Kansas, by Kenshu Shimada. The work documents tooth morphology, dental formula, and ontogenetic variation. Shimada demonstrates that C. mantelli had up to 34 teeth in the upper row and 36 in the lower row, totaling multiple functional rows. Teeth increase gradually in size from the symphysis to the jaw angle, reaching up to 5 cm in the largest functional teeth. The study reveals morphological differences between anterior and lateroposterior teeth used to infer prey capture mechanism. This paper, along with the anatomical article of the same year, is the primary reference for identification of isolated C. mantelli teeth in fossil records.

Paleogeographic map of North America during the late Campanian (~75 Ma) showing the Western Interior Seaway, the shallow epicontinental sea in which Cretoxyrhina mantelli was the apex predatory shark. The seaway separated Laramidia to the west from Appalachia to the east. Modified after Blakey.

Vertebral centra of Cretoxyrhina mantelli and related species from the Smoky Hill Chalk Member of the Niobrara Formation in Kansas, documenting the morphological variability studied by Shimada and others.

Comprehensive skeletal description of Cretoxyrhina mantelli based on the most complete known specimens from the Niobrara Chalk of Kansas. Shimada describes in detail the cartilaginous neurocranium, vertebral column (with a count of approximately 230 vertebrae), fin elements, and branchial elements. The work reveals that C. mantelli had anatomy consistent with placement within Lamniformes, with morphofunctional characteristics close to the modern mako shark (Isurus). This is the primary anatomical reference study for the species and established the framework for all subsequent morphological and phylogenetic analyses. The detailed description of the neurocranium, especially well preserved in specimen FHSM VP-2187, revealed data on the sensory capabilities of the Cretaceous predator.

Interpretive drawings of the Cretoxyrhina mantelli KUVP-247 and FHSM VP-2187 skeletons, the two most complete specimens known, basis of Shimada's (1997) anatomical studies.

Cartilaginous skeleton of Cretoxyrhina mantelli (FHSM VP-2187) at the Sternberg Museum of Natural History, Kansas. This is the most complete known specimen and the primary subject of Shimada's (1997) study.

Analysis of the paleoecological relationships of Cretoxyrhina mantelli based on predation evidence preserved in fossil specimens from the Niobrara Chalk of Kansas. Shimada documents C. mantelli bite marks on mosasaurs, teleosts including Xiphactinus, and possibly plesiosaurs. The work demonstrates that C. mantelli occupied the top of the food chain in the Western Interior Seaway, competing with or preying on the largest marine vertebrates of the time. The study is fundamental for reconstructing the ecological interactions of the Cretaceous Kansas ecosystem and establishes C. mantelli as the apex predator of the Western Interior Seaway during the Coniacian-Campanian.

Scene from the Cretaceous Western Interior Sea of Kansas by Dmitry Bogdanov (2008), showing Cretoxyrhina and Squalicorax around a dead hadrosaur. The depicted paleoenvironment corresponds to that described by Shimada (1997).

Reconstruction of Cretoxyrhina mantelli by Dmitry Bogdanov (2008). The robust hydrodynamic body morphology reflects the apex predator position in the Western Interior Seaway documented by Shimada (1997).

First study of periodic growth increment bands in the vertebral centra of Cretoxyrhina mantelli, providing the first data on growth rates and life history parameters of this extinct lamniform shark. Shimada demonstrates that growth bands are comparable to those of modern lamniform sharks and uses them to estimate that 5-meter individuals would be between 20 and 30 years old. Length at birth is estimated at 1.28 m and asymptotic length at 6.91 m. This pioneering work opens the field of life history study of extinct sharks via vertebra analysis and establishes methodological protocols followed in subsequent studies of other extinct species.

Fossil vertebrae of Cretoxyrhina mantelli at the Museo di Sant'Anna D'Alfaedo, Italy. The periodic growth rings in the vertebrae were studied by Shimada (1997) to determine the animal's age and growth rate.

Monument Rocks, a Cretaceous chalk formation in Kansas, one of the iconic sites where Niobrara sediments preserved exceptional fossils of Cretoxyrhina mantelli.

Quantitative analysis of the ontogenetic development and life history strategies of Cretoxyrhina mantelli based on the vertebral growth increment model. Shimada uses the von Bertalanffy growth function with parameters derived from vertebral bands to create detailed growth curves. Asymptotic length (L∞) is estimated at 6.91 m total length. The study demonstrates that C. mantelli grew rapidly in the first years of life, reaching more than half of maximum length by around 10 years, and that 5-meter individuals would have been probably 20-30 years old. These data are comparable to those of the great white shark and the mako shark, suggesting similar ecology and metabolism.

Scale diagram of the three most significant Cretoxyrhina mantelli specimens: FHSM VP-2187 (most complete), CMN 4096 (largest from North America), and NHMUK PV OR 4498 (largest known). Shimada (2008) estimated maximum length based on vertebral increments.

Size comparison diagram of Cretoxyrhina mantelli with a human figure, showing the impressive size of the Cretaceous predator. The scale reflects the growth data analyzed by Shimada (2008).

Analysis of mosasaur remains with bite marks attributed to Cretoxyrhina mantelli from the Niobrara Chalk of Kansas, providing direct evidence of predatory behavior. Shimada documents several mosasaur bones, including vertebrae and ribs, with bite marks characteristic of the cylindrical, smooth teeth of C. mantelli. Marks include deep incisions, teeth embedded in bones, and multiple bite patterns suggesting feeding by grasping. This work is fundamental for reconstructing the Western Interior Seaway food chains and documents for the first time directly that C. mantelli attacked and consumed mosasaurs.

Illustration of Cretoxyrhina attacking the sea turtle Protostega, by Foolp. This predatory behavior on large marine vertebrates is documented by bite marks studied by Shimada (1997).

Reconstruction of Cretoxyrhina mantelli by Damouraptor, based on Shimada (1997) and Sternes and Shimada (2018). The body morphology shows the capacity for predation on large marine vertebrates.

Study documenting the first evidence of Cretoxyrhina mantelli preying on pterosaurs, based on a Pteranodon specimen from the Niobrara Formation that preserves a C. mantelli tooth embedded in a bone and a vertebra with a bite mark. Hone, Witton and Habib reconstruct the predation scenario: a pteranodon probably resting on the sea surface was attacked by the shark from below. The work includes artistic illustration of the event by Mark Witton. The discovery expands C. mantelli's prey spectrum to include pterosaurs, demonstrating that this predator was not limited to strictly aquatic prey.

Scientific illustration by Mark Witton (2018) for the Hone et al. article, showing Cretoxyrhina attacking Pteranodon at the surface of the Western Interior Seaway. The artist notes the predatory behavior is speculative but biologically plausible.

Reconstruction of Cretoxyrhina mantelli by Dmitry Bogdanov showing the shark in profile. Hone et al. (2018) demonstrated that this predator attacked even pterosaurs such as Pteranodon.

Figure 1: Mounted Pteranodon and close up of the neck. (A) mounted Pteranodon sp. skeleton LACM 50926 on display in the Los Angeles county museum with highlighted section of the vertebrae shown below; (B) Close up of the vertebral series and shark tooth (indicated by an arrow). Cervical vertebrae III–VII are indicated. Scale bar is 50 mm—this is an approximate value based on published measurements of the vertebrae. Image credit: (A) Stephanie Abramowicz, courtesy Dinosaur Institute, Natural Hist

Figure 2: Two close up views of the Cretoxyrhina mantelli tooth with tracings. (A) left dorsolateral view; (B) left dorsoventral view showing its intimate association with cervical vertebra IV. The tooth is highlighted in medium grey, the 4th cervical vertebra in pale grey and the 5th cervical in dark grey. Abbreviations: ns neural spine, prz prezygopophysis, psz postzygopophysis, st shark tooth. Image credit: David Hone. Download full-size image DOI: 10.7717/peerj.6031/fig-2

Figure 3: Cretoxyrhina mantelli anterior teeth. Tracing of Cretoxyrhina mantelli anterior teeth from Bourdon & Everhart (2011) , their figure 5, mirrored from their original). (A) position 3 in the jaw; (B) position 4; (C) LACM 50926 tooth. The bases of the teeth are shaded in pale grey and the enamel is dark grey. Image credit: David Hone. Download full-size image DOI: 10.7717/peerj.6031/fig-3

Figure 4: Restored scene of Cretoxyrhina attacking Pteranodon . Life reconstruction of a c. 2.5 m long breaching Cretoxyrhina mantelli biting the neck of a 5 m wingspan Pteranodon longiceps , a scene inspired by LACM 50926. The predatory behaviour of this scene is speculative with respect to the data offered by the specimen, but reflects the fact that Cretoxyrhina is generally considered a predatory species, the vast weight advantage of the shark against the pterosaur (see text), and the juvenil

Description of large Cretoxyrhina mantelli deadfalls from the Upper Cretaceous of northeastern Italy, extending the known range of the species to Europe and documenting the ecological role of C. mantelli carcasses in deep-sea ecosystems. Amalfitano and collaborators describe specimens preserving articulated vertebrae, teeth, and cranial fragments of large individuals. The study reveals that C. mantelli carcasses served as a substrate for communities of bottom-dwelling invertebrates, similar to what occurs with modern cetacean carcasses. This work significantly expands the known paleogeographic distribution of C. mantelli beyond the Western Interior Seaway.

Fossil oysters Pseudoperna congesta encrusting a Platyceramus platinus shell, Smoky Hill Member, Niobrara Formation (Upper Cretaceous), Kansas, illustrating the shared marine palaeoenvironment of Cretoxyrhina.

Reconstruction of Cretoxyrhina mantelli by Damouraptor (2022). Amalfitano et al. (2019) demonstrated that the species' geographic range was much wider than thought, including the European Tethys Sea.

Analysis of vertebral growth in Late Cretaceous lamniform sharks including Cretoxyrhina mantelli, providing revised estimates of maximum body size and growth patterns across ontogeny. Newbrey and collaborators processed vertebral increment data from multiple C. mantelli specimens and produced size estimates incorporating greater specimen diversity than Shimada's earlier study (1997). Based on an especially large tooth, the maximum size estimate reaches 8 meters in length, although the typical length for adults is 5-7 m. The work also documents vertebral centra from three different localities in Kansas, demonstrating the abundance of C. mantelli in the Western Interior Seaway.

Fossil crinoids Uintacrinus socialis preserved in the chalk of the Niobrara Formation (Upper Cretaceous) in western Kansas, representative of the benthic fauna that co-inhabited the Western Interior Seaway with Cretoxyrhina.

Map of the Western Interior Seaway at approximately 95 Ma, showing the extent of this epicontinental sea across North America during the Cenomanian. The seaway formed the habitat of the early populations ancestral to Late Cretaceous Cretoxyrhina mantelli, studied in the context of ontogeny and life history by Shimada and colleagues.

Analysis of an associated dentition of Cretoxyrhina mantelli from the Smoky Hill Chalk of western Kansas, documenting dental morphology and formula, and comparing with previously known material. Bourdon and Everhart describe a rare set of teeth associated in situ that allows precise reconstruction of the complete dental pattern of the species. The work reveals variations in tooth morphology along the rows that had not been fully documented by Shimada (1997). The analysis demonstrates that C. mantelli had greater dental variability than thought, which may reflect ontogenetic specialization of the dentition for different types of prey at different life stages.

Map showing the Cretaceous Western Interior Seaway dividing North America into the landmasses of Laramidia and Appalachia. The associated dentition of Cretoxyrhina mantelli analyzed by Bourdon and Everhart (2011) was recovered from Niobrara Formation deposits formed at the margins of this seaway.

Ventral view of the mouth of specimen FHSM VP-2187, photograph by Dr. Amelia Zietlow, showing the oral cavity with Cretoxyrhina mantelli teeth. This perspective complements the dental data of Bourdon and Everhart (2011).

Fundamental taxonomic revision demonstrating that several Cretaceous lamniform shark species previously placed in distinct genera are junior synonyms of Cretoxyrhina mantelli. Ward analyzes the type material of Hypotodus verticalis, H. robustus and H. heinzelini and concludes that all belong to C. mantelli, significantly simplifying the taxonomy of the group. This revision explains why European specimens were described as different species from Kansas forms and consolidates C. mantelli as a single species of cosmopolitan distribution. The taxonomic clarification is essential for correctly interpreting the paleogeographic distribution and biodiversity of Late Cretaceous lamniformes.

Cross-section of Upper Cretaceous units in southwestern Wyoming, showing the stratigraphic continuity of the Western Interior Seaway marine deposits that preserve Cretoxyrhina mantelli fossils.

Cranial region of specimen KUVP 247 of Cretoxyrhina mantelli at the University of Kansas. Ward's (1988) taxonomic revision consolidated the interpretation of European and American materials as belonging to the same species.

Analysis of Late Cretaceous and Danian shark faunas including Cretoxyrhina mantelli from Europe, providing biostratigraphic and paleoecological context for the species' final occurrence in the European record. Siverson documents that C. mantelli persisted in Europe until close to the end of the Cretaceous, with the last European records from the upper Campanian. The work provides data on the shark fauna composition in the European Late Cretaceous and helps understand the causes of C. mantelli's extinction at the K-Pg event. The biostratigraphic analysis allows correlation of the European and American records of the species.

Paleogeographic map of North America during the late Campanian of the Late Cretaceous, showing the Western Interior Seaway. Siverson (1992) correlated European shark faunas with North American ones from this period.

Rock sample from the Niobrara Formation (GeoDIL number 2856), representing the Upper Cretaceous chalk substrate deposited on the floor of the Western Interior Seaway, where sharks like Cretoxyrhina lived and left their fossils.

Comprehensive natural history of the Western Interior Sea and its fauna, including detailed accounts of Cretoxyrhina mantelli based on decades of fieldwork in Kansas by Mike Everhart. The book documents hundreds of C. mantelli teeth collected in western Kansas and describes several predation events documented by bite marks in other fossils. Everhart collected and described evidence of C. mantelli preying on mosasaurs, plesiosaurs, and large fish. The work is the most accessible and comprehensive reference on the paleoecology of C. mantelli in the context of the complete Western Interior Sea ecosystem, and is widely cited in paleoichthyological and general paleontological literature.

Posterior region of the KUVP 247 skeleton of Cretoxyrhina mantelli at the University of Kansas. Specimens like this were extensively documented by Everhart (2004) in his natural history of the Western Interior Sea.

Cranial region of specimen FHSM VP-2187 at the Sternberg Museum of Natural History, Kansas. Everhart (2004) described this and other specimens in detail in his work on the Western Interior Sea.

Shimada (2005) conducted a phylogenetic analysis of lamniform sharks including Cretoxyrhina mantelli, evaluating which dental characters are informative for group systematics. The study placed Cretoxyrhina within Lamnidae sensu lato, corroborating earlier analyses based on dental morphology, and demonstrated that the morphological convergence between modern white sharks and Cretoxyrhina results from parallel evolution rather than immediate common ancestry.

Opalized Niobrara from Ellis County, Kansas (September 2018), illustrating the mineralogical diversity of the formation whose sedimentary matrix preserves isolated teeth and vertebrae of Cretaceous lamniform sharks.

Opalized Niobrara from Ellis County, Kansas (September 2018), showing the lithological diversity of the formation whose marine deposits are rich in teeth and vertebrae of Cretaceous lamniform sharks.

Full-size T-rex animatronic from the Jurassic Park franchise, with the iconic red Jeep — Amaury Laporte · CC BY 2.0