Champsosaurus
Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Choristodera
Suborder: Neochoristodera
Genus: Champsosaurus
Type Species: Champsoaurus annectens Cope, 1876 (nomen dubium) (type) meaning "Crocodile Saurian."
Described by Edward Drinker Cope, 1877.
-Champsosaurus albertensis, Parks, 1927
-Champsosaurus ambulator, Brown, 1905
-Champsosaurus annectens, Cope, 1876 (nomen dubium) (type)
-Champsosaurus dolloi, Sigogneau-Russell, 1979
-Champsosaurus gigas, Erickson, 1972
-Champsosaurus laramiensis, Brown, 1905
-Champsosaurus lindoei, Gao & Fox, 1998
-Champsoaurus natator, Parks, 1933
-Champsosaurus norelli Brownstein, 2022
-Champsoaurus tenuis Erickson, 1981
Synonyms:
-Champsosaurus australis, Cope, 1881 [nomen vanum]
-Champsosaurus brevicollis, Cope, 1876 [nomen vanum]
-Champsosaurus inelegans, Parks, 1933
-Champsosaurus inflatus, Parks, 1933
-Champsosaurus profundus Cope, 1876 [nomen vanum]
-Champsosaurus puercensis Cope, 1882 [nomen vanum]
-Champsosaurus saponensis Cope, 1882 [nomen vanum]
Current Park Population: (13; all adults; 7 male, 6 female)
Park Diet: Fish, thawed mice and rats, and pre-killed chicken and parts of pigs and sheep.
Natural Diet: Fish and small reptiles, amphibians, birds, mammals, young, and baby dinosaurs.
Lifespan: 40 years
Habitat: Wetlands, Swamps, rivers, streams, and ponds.
Native Ecosystem: North America, Laramadia and Appalachia, Hell Creek Formation, Judith River Formation, Horseshoe Canyon Formation, Sentinel Butte Formation, Bullion Creek Formation, Dinosaur Park Formation, Tullock Formation, Frenchman Formation, Puerco Formation, Torrejonian Formation, Sentinel Butte Formation, Ravenscrag Formation, Alberta, Saskatchewan, and Arctic, Canada, Montana, North Dakota, New Mexico, Texas, Colorado, and Wyoming, and Europe, Belgium, and France. Late Cretaceous, Campanian to Paleocoene, 83.6-64 Million Years Ago.
Breeding Season: April-September
Gestation Period: Four-Five Weeks
Eggs Laid: 20-50 eggs
Hatching Time: Three-Six Weeks
Danger Level: 5 out of 10.
Summary: There are many examples of convergent evolution in the natural and prehistoric world. Champsosaurus for example, is extremely similar to crocodilians in body form and behavior. However, this animal is not a crocodilian, but a member of a far more ancient brand of reptile that has left no living relatives, a Choristodere.
History of Research: Champsosaurus was the first member of the Choristodera to be described. Champsosaurus was named by Edward Drinker Cope in 1876, from isolated vertebrae found in Late Cretaceous strata of the Judith River Formation on the banks of the Judith River in Fergus County, Montana. Cope designated C. annectens as the type species rather than the first named C. profundus due to the larger number of vertebrae he attributed to the species. C. annectens was based on 9 isolated vertebral centra (AMNH FR 5696) that were not figured in the paper of which two are now lost. Cope named several other species between 1876 and 1882, also based on isolated vertebrae. Barnum Brown in 1905 described the first complete remains of Champsosaurus and noted that one of the species attributed to Champsosaurus by Cope in 1876, C. vaccinsulensis represented indeterminate plesiosaur remains and that the vertebrae that Cope used to diagnose his species of Champsosaurus were heavily eroded and the diagnostic features varied substantially along the spinal column, and were not diagnostic to species level, including the remains that Cope attributed to the type species C. annectens. The conclusion that C. annectens was nondiagnostic was supported by William Parks in 1933.
Brown in 1905 named two species of Champsosaurus. One was C. ambulator, named from the specimen AMNH 983, a fragmentary skeleton with a partial skull found in the Hell Creek Formation of Montana. The other was C. laramiensis, named from AMNH 982, a nearly complete skeleton and skull, also found in the Hell Creek Formation. Parks in 1927 named C. albertensis from ROM 806, a partial skeleton lacking the skull, found in the Horseshoe Canyon Formation in Alberta, Canada. Parks in 1933 named the species C. natator from an incomplete skeleton with a fragmentary skull (TMP 81.47.1) found in the Belly River Group in the Red Deer River valley in Alberta. In 1979, Denise Sigogneau-Russell named the species C. dolloi from remains found in the Paleocene of Belgium. In 1972, Bruce Erickson named the species C. gigas from SMM P71.2.1, a partial skeleton and skull found in the Sentinel Butte Formation, Golden Valley County, North Dakota. Erickson subsequently in 1981 named the species C. tenuis from SMM P79.14.1, a partial skeleton and skull found in the Bullion Creek Formation, North Dakota. In 1998 K. Q. Gao and Richard Carr Fox described the species C. lindoei from UALVP 931, a nearly complete skeleton with skull and jaws from the Dinosaur Park Formation in Alberta. The publication also thoroughly reviewed Champsosaurus, diagnosing most species except for C. ambulator and C. laramiensis.
Fossils of Champsosaurus have been found in North America (Alberta, Saskatchewan, Montana, New Mexico, Texas, Colorado, and Wyoming) and Europe (Belgium and France), dating from the Upper Cretaceous to the late Paleocene. Remains tentatively referred to as Champsosaurus are known from the high Canadian Arctic, dating to the Coniacian–Turonian, a time of extreme warmth.
Taxonomy: Sixteen species of Champsosaurus have been named, of which seven are presently considered valid. The type species Champsosaurus annectens Cope, 1876 is considered to be dubious. The only named European species C. dolloi Sigogneau-Russell 1979 was considered to be too fragmentary to warrant a new species by Gao and Fox in 1998.
Species: Champsosaurus ambulator
Author: Brown
Year: 1905
Status: Valid
Temporal Range: Maastrichtian-Paleocene
Location: United States (Montana)
Formation: Hell Creek & Tullock
Notes & Description: Distinguished from C. laramiensis by having robust limbs and limb girdles
Species: Champsosaurus laramiensis
Author: Brown
Year: 1905
Status: Valid
Temporal Range: Maastrichtian-Paleocene
Location: United States (Montana and New Mexico) and Canada (Saskatchewan)
Formation: Hell Creek, Frenchman, Tullock, Puerco, Torrejonian
Notes & Description: Synonyms C. australis Cope, 1881, C. puercensis Cope, 1881, C. saponensis Cope, 1881 distinguished from C. ambulator by having gracile limbs and long bones.
Species: Champsosaurus albertensis
Author: Parks
Year: 1927
Status: Valid
Temporal Range: Campanian-Maastrichtian
Location: Canada (Alberta)
Formation: Horseshoe Canyon
Notes & Description: Distinguished from other species of Champsosaurus based on proportionately short epipodials, though Gao and Fox (1998) suggest that this may not be taxonomically significant.
Species: Champsosaurus natator
Author: Parks
Year: 1933
Status: Valid
Temporal Range: middle-late Campanian
Location: Canada (Alberta)
Formation: Dinosaur Park
Notes & Description: Relatively large species (~ 2 meters in length) syn. C. profundus Cope, 1876, C. brevicollis Cope, 1876, C. inelegans Parks, 1933, C. inflatus Parks, 1933 distinguished by " (1) a more robust skull than the contemporaneous C. lindoei; (2) laterally swollen lower temporal bar; (3) lower temporal fenestra expanded mediolaterally; (4) expansion of the postfrontal separating the postorbitals from the frontals"
Species: Champsosaurus gigas
Author: Erickson
Year: 1972
Status: Valid
Temporal Range: Paleocene
Location: United States (North Dakota) and Canada (Saskatchewan)
Formation: Sentinel Butte and Ravenscrag
Notes & Description: Largest species of the genus, reaching a length of approximately meters. Distinguished by "(1) parietal table strongly projecting laterally at anterior margin of superior temporal fenestra; (2) posterior part of parietal table narrower than in other species of comparable size; (3) postorbital extending anteromedially to meet frontal and parietal, preventing post-frontal-parietal contact"
Species: Champsosaurus tenuis
Author: Erickson
Year: 1981
Status: Valid
Temporal Range: Paleocene
Location: United States (North Dakota)
Formation: Bullion Creek
Notes & Description: Distinguished by "(1) An extremely long and slender snout; (2) postcranial skeleton with narrow shoulder girdle; (3) clavicles short and deeply concave anteriorly; (4) limbs reduced in length"
Species: Champsosaurus lindoei
Author: Gao and Fox
Year: 1988
Status: Valid
Temporal Range: middle-late Campanian
Location: Canada (Alberta)
Formation: Dinosaur Park
Notes & Description: A relatively small member of the genus characterized by "(1) snout significantly more slender in proportion to the skull size, and the bulla on the snout is proportionately larger; (2) the pterygoid flange is weakly developed with a reduced number of teeth; (3) inferior temporal arch is nearly straight, and is not swollen laterally; (4) subtemporal fenestra is rectangular, not oval".
Description: Individuals are dark yellowish green with pale spots over their bodies, a circle around the neck region, and stripes on the tail, on the pale underbelly there were black spots, and jaws were striped from the back base to the tip of the snouts.
Size: Most species grew to about 1.50 m (5 ft) long, though Champsosaurus gigas, the largest species of the Paleocene Champsosaurus gigas, reached 3–3.5 m (10–12 ft) in length which seems to have been around the specific size the Hell Creek species could also reach.
Anatomy/Skull: The skull of Champsosaurus is dorsoventrally flattened, while the temporal arches are expanded posteriorly (towards the back of the skull) and laterally (away from the midline), giving the skull a heart-shaped appearance when viewed from above. The snout is greatly elongated and gharial-like, making up around half the length of the skull, and at least four times as long as it is wide, with the opening of the nostrils at the end of the snout. The openings of the ears are located on the underside of the skull. The body is flat and streamlined, with heavy gastralia (rib-like bones situated in the belly). Compared to other choristoderes, the lacrimal bone is reduced in size to a small triangle, the postorbital bone does not form part of the orbit (eye socket), there is no contact between the premaxilla and the vomer bones, an internarial bone is present, the choanae are located posteriorly in correlation to the elongation of the vomer, the interpterygoid vacuity is small and completely enclosed by the pterygoid bones and located near the posterior margin of the suborbital fenestra, the shape of the suborbital fenestra is shortened and kidney like, the articulation between the pterygoid and the parasphenoid is fused, the joint between the skull and the lower jaws is anterior to level of the occipital condyles, the neomorphic bone forms most of the border of the post temporal fenestra, the paroccipital process is strongly deflected downwards, the basal tubera of the basisphenoid are wing-like in shape and expanded backwards and downwards, the mandibular symphysis (connection of the two halves of the lower jaw) is elongated to over half the length of the tooth row, and the splenial bone strongly intervenes in the mandibular symphysis.
Internal cranial Anatomy: The braincase of Champsosaurus is poorly ossified at the front of the skull (anterior), but is well ossified in the rear (posterior) similar to other diapsids. The cranial endocast (space occupied by the brain in the cranial vault) is similar to that of basal archosauromorphs, being proportionally narrow in both dorsoventral and lateral axes, with an enlarged pineal body and olfactory bulbs. The optic lobes and flocculi are small in size, indicating only average vision ability at best. The olfactory chambers of the nasal passages and olfactory stalks of the braincase are reasonably large, indicating that Champsosaurus probably had good olfactory capabilities (sense of smell). The nasal passages lack bony turbinates. The semicircular canals are most similar to those of other aquatic reptiles. The expansion of the sacculus indicates that Champsosaurus likely had an increased sensitivity to low-frequency sounds and vibrations. The absence of an otic notch indicates that Champsosaurus lacked a tympanum, and probably had a poor ability to detect airborne sounds.
Teeth: Champsosaurus, like many of its fellow neochoristoderes, features teeth with striated enamel of the tooth crown with enamel infolding at the base. Anterior teeth are typically sharper and more slender than posterior teeth. Like other choristoderes, Champsosaurus possessed palatal teeth (teeth present on the bones of the roof of the mouth), with longitudinal rows present on the pterygoid, palatine, and vomer, alongside a small row on the flange of the pterygoid. The palatine teeth of Champsosaurus are located on raised platforms of bone, though the wideness of the platforms, the sharpness, and the orientation of teeth vary between species. The orientation of the teeth varies in the jaw, with the posterior teeth being orientated backward. The palatal teeth, likely in combination with a fleshy tongue, probably aided in gripping and swallowing prey.
Skin: Skin impressions of Champsosaurus have been reported. They consist of small (0.6-0.1 mm) pustulate and rhomboid scales, with the largest scales being located on the lateral sides of the body, decreasing in size dorsally, no osteoderms were present.
Classification: Champsosaurus belongs to the Neochoristodera, a clade within Choristodera, the members of which are characterized by elongated snouts and expanded temporal arches. The group first appeared during the Early Cretaceous in Asia and is suggested to have evolved in the regional absence of aquatic crocodyliformes. While Neochoristodera is a well-supported grouping, the relationships of the members of the group to each other are uncertain, with the clade having been recovered as a polytomy in recent analyses.
Paleobiology: Champsosaurus is thought to have been highly specialized for aquatic life. Erickson 1985 suggested that the expanded temporal arches, which likely anchored powerful jaw muscles, and elongated snout allowed Champsosaurus to prey on fish akin to modern gharials, with these adaptations allowing rapid movement of the head and jaws for prey capture. A study in 2021 found that the middle and posterior neck vertebrae of Champsosaurus were adapted for lateral movement and that Champsosaurus may have fed by laterally sweeping its head, using its slender jaws to grab individual fish from shoals, akin to how modern gharials feed. The mechanism of head movement is different from that of gharials, where lateral movement occurs at the head-neck joint. It is unlikely that Champsosaurus fed by intertial feeding (where the prey is temporarily let go and the head moved forwards to force the prey deeper into the throat), but that the prey was moved down the throat by the tongue in combination with the palatal dentition. Erickston 1985 proposed that the position of the nostrils at the front of the snout allowed Champsosaurus to spend large amounts of time at the bottom of water bodies, with the head being angled upwards to allow the snout to act like a snorkel when the animal needed to breathe. However, later studies suggested that the neck vertebrae of Champsosaurus only had a limited ability to flex upwards. Champsosaurus co-existed with similarly sized aquatic crocodilians and at some Paleocene localities with fellow neochoristodere Simoedosaurus, though in assemblages where Champsosaurus occurs, longirostrine (long-snouted) gharial-like crocodilians are absent, suggesting that there was niche differentiation. Previously, two species of Champsosaurus were identified from the Tullock Formation in Montana. However, these differences are now thought to be sexually dimorphic, with presumed females possessing robust limb bones. Non-deformation-related fusion of the sacral vertebrae is also observed in specimens with robust limb bones. These are hypothesized to be related to breeding behavior, with the more robust limb bones and fused sacrals of the females allowing them to move onto land to lay eggs.
Social Behavior: They are mostly solitary and sometimes aggregate in floats to bask or breed.
Diet: Thoracosaurus preyed on fish in the waterways and any small animal or young dinosaur that came to the shore to drink or swim.
Interactions with other species: They are normally ignored by the large dinosaurs often getting out of their way, but could occasionally prey on small dinosaurs, Thescelosaurus, Leptoceratops, Trierarchuncus, Acheroraptor, Pectinodon, the pterosaur, Quetzalcoatlus lawsonii, and young dinosaurs from Pachycephalosaurus, Ornithomimus, Triceratops, Torosaurus, Edmontosaurus, Alamosaurus, Anzu, Ankylosaurus, and Tyrannosaurus. They occasionally prey on small animals like Dinilysia and Didelphodon.
The large adult herbivores would stomp and chase off the Crocodilian if it grabs their head by mistake. Groups of Dromaeosaurus, Pectinodon, Acheroraptor, and Quetzalcoatlus would mob the Crocodilian, and occasionally T. Rex would prey on the Crocodilian if given the chance.
Champsosaurus lived alongside other crocodilians like Thoracosaurus, they normally ignore one another as they have different niches and lifestyles, and they can compete over nesting sites.
Extinction: Surpisngliyng like Crocodilians like Thoracosaurus, Although their group is now entirely gone, this animal did survive the great extinction and right through into the Eocene.
Danger Tip: Like all Crocodiles, Champsosaurus should be avoided as if they get close to the water and they are attracted to splashing they will grab you and drag you into the depths. To get out, punch it in the nostrils which it's most sensitive to and it will let go.
Significant Events: The Team encounters a float of Champsosaurus along a float of Thoracosaurus on the third day of the First mission, in the slow-moving river alongside other crocodilians and reptiles. A group consisting of Lynn, May, Muscleman, Charlie, Jake, Finn, Skips, and Mordecai used canned fish for bait while splashing the water with sticks and getting the Thoracosaurus and Champsosaurus, and another crocodilian floats charging through the portal to the park. They now reside in the Hell Creek Forest Building.
Hell Creek Forest Building Crocodile Pit: It is a large pit in the very center of the building and has a bridge built over it for staff and future guests and there are glass underwater viewing windows. Within it was a large lake divided into four portions for the four rescued crocodilian floats of crocodilian. Champsosaurus live in a paddock that consists mostly of water since they live an aquatic lifestyle with a sandy bank for them to bask and lay their eggs.
Conclusion: Champsosaurus helps us understand convergent evolution between different similar non-related species with modern-day and extinct animals. The Champsosaurus, although not a crocodile, makes an important snapping addition to Paleo Park.
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