The Prehistoric Park Animal Field Guide Volume 1

by WildExpert24

As a Prehistoric Park employee, you get the privilege to work with the likes of previously extinct animals. However, if you want to survive longer than five minutes, then you need to have knowledge of its inhabitants. From the world of Cartoon's Prehistoric Park, this Guide will give you info on behavior, diet, lifespan, and more. Welcome to the Ultimate Prehistoric Guidebook.

18. Thescelosaurus

Thescelosaurus

Scientific Classification

Kingdom: Animalia

Phylum: Chordata

Clade: Dinosauria

Order: Ornithischia

Family: Thescelosauridae

Subfamily: Thescelosaurinae

Genus: Thescelosaurus

Type Species: Thescelosaurus neglectus meaning ""wonderful", "godlike", "marvellous", or "wondrous" Lizard."

Species:

-Thescelosaurus neglectus meaning " Neglected "godlike", Lizard,"

-Thescelosaurus garbanii meaning "Garbani's "marvellous" Lizard," Morris, 1976

Thescelosaurus assiniboiensis meaning "Assiniboine's "wondrous" Lizard," Brown, Boyd, & Russell, 2011

Described by Charles Whitney Gilmore, 1913

Synonym: Bugenasaura Galton, 1995

Current Park Population: (27; 18 adults, 9 youngsters; 13 male, 14 female)

Park Diet: Chicken feed, blueberries, Ferns, low shrubs, flowers, mulberry leaves, crickets, and mealworms,

Natural Diet: Ferns, low shrubs, flowers, small insects, small animals, and eggs.

Lifespan: 18 years

Habitat: Open areas like floodplain swamps, fern prairies, and open-canopy forests with large amounts of food often near streams and waterways.

Native Ecosystem: Western North America, on what was then an island continent known as Laramidia. Hell Creek Formation, Lance Formation, Evanston Formation, Scollard Formation, Laramie Formation, Denver Formation, Southwestern Alberta and Saskatchewan, Canada, Montana, South Dakota, Wyoming, Colorado, and possibly New Mexico and Texas, USA, 68-66 Million Years Ago, Maastrichtian Stage.

Breeding Season: June and July.

Gestation Period: two months

Eggs Laid: eight to nineteen eggs

Hatching Time: Two to Three weeks, depending on atmospheric moisture.

Danger Level: 3 out of 10.

Summary: One of the Swiftest small dinosaurs of the Cretaceous are the Thescelosaurus. They are the Cretaceous equivalne of deer and antelope as they live in large flocks as a form of safety in numbers. There have been many preservation and completeness of specimens which an tell us more about these small dinosaurs.

Disocovery, History, and Species: The type specimen of Thescelosaurus (USNM 7757) was discovered in 1891 by paleontologists John Bell Hatcher and William H. Utterback, from beds of the late Maastrichtian-age Upper Cretaceous Lance Formation of Niobrara County (at the time part of Converse County), Wyoming, USA. The skeleton, however, remained in its shipping crates for years until Charles W. Gilmore of the Smithsonian Institution's National Museum of Natural History had it prepared and described it in a short paper in 1913, naming it T. neglectus (neglectus: "neglected"). At the time, he thought it was related to Camptosaurus. He provided a detailed monograph in 1915, describing the well-preserved skeleton. The type specimen was found largely in natural articulation and was missing only the head and neck, which were lost due to erosion. The name comes from the surprise Gilmore felt at finding such a good specimen that had been unattended to for so long. He considered it to be a light, agile creature, and assigned it to the Hypsilophodontidae, a family of small bipedal dinosaurs.

Other remains of similar animals were found throughout the late 19th century and 20th century. Another well-preserved skeleton from the slightly older Horseshoe Canyon Formation, in Alberta, Canada, was named T. warreni by William Parks in 1926. This skeleton had notable differences from T. neglectus, and so Charles M. Sternberg placed it in a new genus, Parksosaurus, in 1937. Sternberg also named an additional species, T. edmontonensis, based on another articulated skeleton, this time including a partial skull (NMC 8537), and drew attention to the genus' heavy build and thick bones. Due to these differences from the regular light hypsilophodont build, he suggested that the genus warranted its own subfamily, Thescelosaurinae. T. edmontonensis has, since Peter Galton's 1974 review, generally been considered a more robust individual (possibly the opposite sex of the type individual) of T. neglectus. However, Boyd and colleagues found that they could not assign it to either of their valid species of Thescelosaurus and regarded the specimen as of uncertain placement within the genus. The other point of contention regarding T. edmontonensis is its ankle, which Galton claimed was damaged and misinterpreted, but which was regarded by William J. Morris (1976) as truly different from T. neglectus.

n his paper, Morris described a specimen (SDSM 7210) consisting of a partial skull with heavy ridges on the lower jaw and cheek, four partial vertebrae, and two finger bones as an unidentified species of Thescelosaurus, from the late Maastrichtian-age Hell Creek Formation of Harding County, South Dakota, USA. He drew attention to its premaxillary teeth and deeply inset toothline which he interpreted as supporting the presence of muscular cheeks. Morris also pointed out the outwardly flaring premaxilla (which would have given it a wide beak) and large palpebrals. This skull was recognized as an unnamed hypsilophodont for many years, until Galton made it the type specimen of new genus and species Bugenasaura infernalis ("large-cheeked lizard belonging to the lower regions", infernalis being a reference to the Hell Creek Formation). Morris also named a new possible species of Thescelosaurus for specimen LACM 33542: ?T. garbanii (with a question mark because he was uncertain that it belonged to the genus). LACM 33542 comprised a large partial hindlimb ("a third larger than described specimens of T. neglectus and Parksosaurus or nearly twice as large as Hypsilophodon") including a foot, tarsus, shin bones, and partial thigh bone, along with five cervical (neck) and eleven dorsal (back) vertebrae, from the Hell Creek Formation of Garfield County, Montana, USA. The specimen was discovered by amateur paleontologist Harley Garbani, hence the name. T. garbanii would have been about 4.5 meters (15 feet) long, greater than average specimens of T. neglectus. Aside from the size, Morris drew attention to the way the ankle was constructed, which he considered to be unique except in comparison with Thescelosaurus edmontonensis, which he regarded as a separate species. Because Morris believed that the ankles of T. garbanii compared favorably to those of T. edmontonensis, he tentatively assigned it to Thescelosaurus. However, the scientific literature has favored Galton's view that T. edmontonensis was not different from T. neglectus (see above). In the same paper that he described Bugenasaura, Galton demonstrated that the features Morris had thought connected T. garbanii and T. edmontonensis were the result of damage to the latter's ankle, so T. garbanii could also be considered distinct from Thescelosaurus. To better accommodate this species, Galton suggested that it belonged to his new genus Bugenasaura as B. garbanii, although he also noted that it could be belong to the similarly sized pachycephalosaurid Stygimoloch, or be part of a third, unknown dinosaur.

Clint Boyd and colleagues published a reassessment of Thescelosaurus, Bugenasaura, and Parksosaurus in 2009, using new cranial material as a starting point. They found that Parksosaurus was indeed distinct from Thescelosaurus, and that the skull of Bugenasaura infernalis was essentially the same as a skull found with a postcranial skeleton that matched Thescelosaurus. Because B. infernalis could not be differentiated from Thescelosaurus, they regarded the genus as a synonym of Thescelosaurus, the species as dubious, and SDSM 7210 as an example of T. sp. They found that LACM 33542, although fragmentary, was a specimen of Thescelosaurus, and agreed with Morris that the ankle structure was distinct, returning it to T. garbanii. Finally, they noted that another specimen, RSM P.1225.1, differed from T. neglectus in some anatomical details, and may represent a new species. Thus, Thescelosaurus per Boyd et al. (2009) is represented by at least two, and possibly three valid species: type species T. neglectus, T. garbanii, and a possible unnamed species. In December 2011, RSM P.1225.1 was assigned to its own species, Thescelosaurus assiniboiensis. It was named by Caleb M. Brown, Clint A. Boyd and Anthony P. Russell and is known only from its holotype, a small, articulated and almost complete skeleton from the Frenchman Formation (late Maastrichtian stage) of Saskatchewan. In April 2022, it was reported that a specimen of Thescelosaurus was found at the Tanis fossil site, supposedly dating to the exact day of the K-Pg extinction, making it the first non-avian dinosaur fossil recovered from that date.

Description: Adultsare covered with dark brown feathers, black feathering around the neck and head, a white throat collar, white eyebrows marking under and above the eyes, dark brown quills on its tail, except the snout, grays legs, a black and white striped tail, the snouts were gray with black beaks which are covered in scales.

The males had small red keratin like a stubby horn on its snout and dark blue throat while the females lack the red keratin nose, and pale yellow throat.

The adolsecents look identical to the females, but lacks the black head and neck.

The juvneiles and hatclings have black downy fluff coats.

Description: Thescelosaurus was a heavily built bipedal animal, probably herbivorous, but potentially not. There was a prominent ridge along the length of both maxillae (the tooth-bearing "cheek" bones), and a ridge on both dentaries (tooth-bearing bone of the lower jaw). The ridges and position of the teeth, deeply internal to the outside surface of the skull, are interpreted as evidence for muscular cheeks. Aside from the long narrow beak, the skull also had teeth in the premaxilla, or upper beak (a primitive trait among neornithischians). Long rod-like bones called palpebrals were present over the eyes, giving the animal heavy bony eyebrows. Its teeth were of two types: small pointed premaxillary teeth, and leaf-shaped cheek teeth. Six small teeth were present in both premaxillae, with a toothless section at the tip of the beak.

Size: The animal's size has been estimated in the 2.5–4.0 m range for length (8.2–13.1 ft)[8] for various specimens, and a weight of 200–300 kilograms (450–660 pounds), with the large type specimen of T. garbanii estimated at 4–4.5 meters (13.1–14.8 feet) long. They are about the heigh around the waist of a human.

Skeleton: Overall, the skeletal anatomy of this genus is well documented, and restorations have been published in several papers, including skeletal restorations and models. The skeleton is known well enough that a detailed reconstruction of the hip and hindlimb muscles has been made.

Thescelosaurs had short, broad, five-fingered hands, four-toed feet with hoof-like toe tips, and a long tail braced by ossified tendons from the middle to the tip, which would have reduced the flexibility of the tail. The rib cage was broad, giving it a wide back, and the limbs were robust. The animals may have been able to move on all fours, given its fairly long arms and wide hands, but this idea has not been widely discussed in the scientific literature, although it does appear in popular works. Charles M. Sternberg reconstructed it with the upper arm oriented almost perpendicular to the body, another idea that has gone by the wayside. As noted by Peter Galton, the upper arm bone of most ornithischians articulated with the shoulder by an articular surface that consisted of the entire end of the bone, instead of a distinct ball and socket as in mammals. The orientation of the shoulder's articular surface also indicates a vertical and not horizontal upper arm in dinosaurs.

Large thin flat mineralized plates have been found next to the ribs' sides. Their function is unknown; they may have played a role in respiration. However, muscle scars or other indications of attachment have not been found for the plates, which argues against a respiratory function. Recent histological study of layered plates from a probable subadult indicates that they may have started as cartilage and became bone as the animal aged. Such plates are known from several other cerapodas.

Skin: For most of its history, the nature of this genus' integument, be it scales or something else, remained unknown. Charles Gilmore described patches of carbonized material near the shoulders as possible epidermis, with a "punctured" texture, but no regular pattern, while William J. Morris suggested that armor was present, in the form of small scutes he interpreted as located at least along the midline of the neck of one specimen. Scutes have not been found with other articulated specimens of Thescelosaurus, though, and Morris's scutes could be crocodilian in origin. In his 2022 documentary, Dinosaurs: The Final Day, Sir David Attenborough reported a Thescelosaurus specimen allegedly killed on the day of the K-Pg extinction, covered in skin impressions that included elongated scales over the legs. One of the paleontologists excavating it was quoted as speculating they had a camouflage function. In a follow-up interview, Paul Barrett has noted that this means Thescelosaurus was not as feathered as hypothesized for other small neornithischians.

The legs and tails were mostly scaly as the restof the bodies were covered on downy fluffy coating. Most recently, research led by paleontologist, Clint Boyd, uncovers more than one Thescelosaurus specimens had a pair of bony, knob-like spurs growing out of each of their forearms.

Classification: Thescelosaurus has generally been allied to Hypsilophodon and other small neornithischians as a hypsilophodontid, although recognized as being distinct among them for its robust build, unusual hindlimbs, and, more recently, its unusually long skull. Peter Galton in 1974 presented one twist to the classic arrangement, suggesting that because of its hindlimb structure and heavy build (not cursorial, or built for running, by his definition), it should be included in the Iguanodontidae. This has not been followed, with Morris arguing strongly against Galton's classification scheme. At any rate, Galton's Iguanodontidae was polyphyletic and not a natural group, and so would not be recognized under modern cladistic usage.

Although Hypsilophodontidae was interpreted as a natural group in the early 1990s, this hypothesis has fallen out of favor and Hypsilophodontidae has been found to be an unnatural family composed of a variety of animals more or less closely related to Iguanodontia (paraphyly), with various small clades of closely related taxa. "Hypsilophodontidae" and "hypsilophodont" are better understood as informal terms for an evolutionary grade, not a true clade. Thescelosaurus has been regarded as both very basal and very derived among the hypsilophodonts. One issue that has potentially interfered with classifying Thescelosaurus is that not all of the remains assigned to T. neglectus necessarily belong to it. Clint Boyd and colleagues found that while the clade Thescelosaurus included the genus Bugenasaura and the species that had been assigned to that genus, there were at least two and possibly three species within Thescelosaurus, and several specimens previously assigned to T. neglectus could not yet be assigned to a species within the genus. It appears to be closely related to Parksosaurus.

The dissolution of Hypsilophodontidae has been followed by the recognition of the distinct family Thescelosauridae. This area of the dinosaur family tree has historically been complicated by a lack of research, but papers by Clint Boyd and colleagues and Caleb Brown and colleagues have specifically addressed these dinosaurs. Boyd et al. (2009) and Brown et al. (2011) found North American "hypsilophodonts" of Cretaceous age to sort into two related clusters, one consisting of Orodromeus, Oryctodromeus, and Zephyrosaurus, and the other consisting of Parksosaurus and Thescelosaurus. Brown et al. (2013) recovered similar results, with the addition of the new genus Albertadromeus to the Orodromeus clade and several long-snouted Asian forms (previously described under Jeholosauridae) to the Thescelosaurus clade. They also formally defined Thescelosauridae (Thescelosaurus neglectus, Orodromeus makelai, their most recent common ancestor, and all descendants) and the smaller clades Orodrominae and Thescelosaurinae.

Paleobiology: Thescelosaurus would have browsed in the first meter or so from the ground, feeding selectively, with food held in the mouth by cheeks while chewing. Thescelosaurus was probably slower than other hypsilophodonts, because of its heavier build and leg structure. Compared to them, it had unusual hindlimbs, because the upper leg was longer than the shin, the opposite of Hypsilophodon and running animals in general. One specimen is known to have had a bone pathology, with the long bones of the right foot fused at their tops, hindering swift movement.

Social Behavior: The Thescelosaurus live in flocks with multiple males, females, and their young as they feed, a sentry will alert the flock of danger.

Dentition and Diet: Examinations of the teeth of Thescelosaurus and comparisons with the contemporary pachycephalosaur Stegoceras suggest that Thescelosaurus was a selective feeder, while Stegoceras was a more indiscriminate feeder, allowing both animals to share the same environment without competing for food.

They mostly feed on ferns, scrubs, flowers, insects, eggs, and small animals. At the park, they are fed mulberry leaves, blueberries, crickets, and mealworms.

Sexual Dimorphism: As discussed more fully under "Discovery, history, and species", it may have been sexually dimorphic, with one sex larger than the other. Juvenile remains are known from several locations, mostly based on teeth.

Reproduction: Based on the spurs recently discovered on their forearms and an observation, Males would engage in males wrestling and slashing one another with their spurs for the right to mate with the females like Roosters in a Cock Fight.

Supposed Fossilized Heart: In 2000, a skeleton of this genus (specimen NCSM 15728) informally known as "Willo", now on display at the North Carolina Museum of Natural Sciences, was described as including the remnants of a four-chambered heart and an aorta. It had been originally unearthed in 1993 in northwestern South Dakota. The authors had found the internal detail through computed tomography (CT) imagery. They suggested that the heart had been saponified (turned to grave wax) under airless burial conditions, and then changed to goethite, an iron mineral, by replacement of the original material. The authors interpreted the structure of the heart as indicating an elevated metabolic rate for Thescelosaurus, not reptilian cold-bloodedness.

Their conclusions have been disputed; soon after the initial description, other researchers published a paper where they asserted that the heart is really a concretion. As they noted, the anatomy given for the object is incorrect (for example, the "aorta" narrows coming into the "heart" and lacks arteries coming from it), it partially engulfs one of the ribs and has an internal structure of concentric layers in some places, and another concretion is preserved behind the right leg. The original authors defended their position; they agreed that it was a type of concretion, but one that had formed around and partially preserved the more muscular portions of the heart and aorta.

A study published in 2011 applied multiple lines of inquiry to the question of the object's identity, including more advanced CT scanning, histology, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. From these methods, the authors found the following: the object's internal structure does not include chambers but is made up of three unconnected areas of lower density material, and is not comparable to the structure of an ostrich's heart; the "walls" are composed of sedimentary minerals not known to be produced in biological systems, such as goethite, feldspar minerals, quartz, and gypsum, as well as some plant fragments; carbon, nitrogen, and phosphorus, chemical elements important to life, were lacking in their samples; and cardiac cellular structures were absent. There was one possible patch with animal cellular structures. The authors found their data supported identification as a concretion of sand from the burial environment, not the heart, with the possibility that isolated areas of tissues were preserved.

The question of how this find reflects metabolic rate and dinosaur internal anatomy is moot, though, regardless of the object's identity. Both modern crocodilians and birds, the closest living relatives of non-avian dinosaurs, have four-chambered hearts (albeit modified in crocodilians), so non-avian dinosaurs probably had them as well; the structure is not necessarily tied to metabolic rate.

Paleoecology:

Temporal and Geographic Range: True Thescelosaurus remains are known definitely only from late Maastrichtian-age rocks, from Alberta (Scollard Formation) and Saskatchewan (Frenchman Formation), Canada, and Wyoming (Lance Formation), South Dakota (Hell Creek Formation), Montana (Hell Creek), and Colorado (Laramie Formation), USA. With the exception of birds, it was one of the last genera of dinosaurs, its remains being found as close as 3 meters to the boundary clay containing the iridium layer that closes the Cretaceous. The Laramie Formation is the oldest formation that Thescelosaurus is known from, and magnetostratigraphy suggests an age of 69-68 Ma for the Laramie Formation. There are reports of teeth from older, Campanian-age rocks, particularly from the Dinosaur Park Formation of Alberta, but these specimens are not from Thescelosaurus and are much more likely those of Orodromeus. More specimens are known than have been officially described for this genus, such as the Triebold specimen, which has been the source of several skeletal casts for museums.

When Galton revisited Thescelosaurus and Bugenasaura in 1999, he described the dentary tooth UCMP 46911 from the Upper Jurassic of Weymouth, England as cf. Bugenasaura. If it is indeed a tooth from a thescelosaur-like animal, this would significantly extend the stratigraphic range of the group.

Habitat:

The preservation and completeness of many of its specimens that have been found indicate that it may have preferred to live near streams. Conflicting reports have been made as to its preferred habitat; two papers suggest it preferred channels to floodplains, but another suggests it preferred the opposite. The possible preference for channels is based on the relative abundance of thescelosaur fossils in sandstones, representing channel environments, in comparison to mudstones, representing floodplain environments. No bonebeds or accumulations of multiple individuals have yet been reported. Dale Russell, in a popular work, noted that Thescelosaurus was the most common small herbivore in the Hell Creek Formation of the Fort Peck area. He described the environment of the time as a flat floodplain, with a relatively dry subtropical climate that supported a variety of plants ranging from angiosperm trees, to bald cypress, to ferns and ginkgos. Although most dinosaur skeletons from this area are incomplete, possibly due to the low preservation potential of forests, Thescelosaurus skeletons are much more complete, suggesting that this genus frequented stream channels. Thus when a Thescelosaurus died, it may have been in or near a river, making it easier to bury and preserve for later fossilization. Russell tentatively compared it to the capybaras and tapirs.

Based on relatives, like Orodromeus and Parksosaurus they would of dig and lived in burrows around the riverbanks using their arms and legs to help dig.

Interactions with other species: Other dinosaurs that shared its time and place include the ceratopsids, Triceratops and Torosaurus, hadrosaurid Edmontosaurus, ankylosaurid, Ankylosaurus, pachycephalosaurian, Pachycephalosaurus, and the theropods Ornithomimus, Troodon, and Tyrannosaurus. Thescelosaurus was also abundant in the Lance Formation. Toe bones from this genus are the most common finds after fossils of Triceratops and Edmontosaurus, and it may have been the most common dinosaur there in life, if the Lance Formation had a preservational bias against small animals.

Thesecelosaurus would of been prey to predators like Acheroraptors, Dromaeosaurus, Dakotaraptors, and young and juvenile Tyrannosaurs, but they can fight back with their legs and sharp beaks. They normally run away into their burrows and sometimes they would swim to get away, but they must avoid the crocodyliforms in the water.

They lived in mixed species herds for protection with other herbivores like Triceratops, Torosaurus, Ankylosaurus, and Ornithomimus often snapping up insects that have been disturbed by their large feet of the herbivores.

Extinction: Thescelosaurus was a member of the last dinosaurian fauna before the Cretaceous–Paleogene extinction event around 66 million years ago. Unfortunately, with the lack of vegetation after the impact of the asteroid combined with other events like forest fires and earthquakes, they slowly starved to death.

Danger Tip: They are normally harmless when approached they run away, but when handled they can kick with their legs, males would claw you with their arm spurs, and their sharp beaks can be very painful.

Significant Events: The Thescelosaurus were encountered alongside other herbivores including Triceratops, Torosaurus, and Ornithomimus gathered at a clearing with a creek close to camp during Day 2 of the Rescue Team's Mission. The Next day, a pack of Tyrannosaurus attacks the multi-species herd, the Thesecelosaurus flock ran off from the large predators.

On the day where the asteroid hits, the Thesecelosaurus flock were found alongside the other herbivores like Triceratops and Torosaurus in the valley snapping up insects that have been disturbed by their large feet of the large herbivores alongside the Ornithomimus where they are pursued by the Female T. Rex stampede down the hill and are funneled by the river on the left side and a wall of fallen logs and debris into the portal to the park. They now reside in the Hell Creek Herbivore Buidling Paddock.

Hell Creek Building Paddocks: The Theseclosaurus lived in one of the outdoor paddocks of the Hell Creek Building which have minimal barriers separating the animals and any humans, staff or otherwise, that would later visit the building. It has a water moat to replicate the waterways these small dinosaurs live in as their burrows are dug around the riverbanks. They normally come out in mornings, evenings, and times when the temperature is cooler as they are mostly hiding.

Conclusion: The Thesecelosaurus are one of the smallest dinosaur residents that don't get as much press and coverage compared to dinosaurs like T. Rex, Ticeratops, and Ankylosauurs. But they are easy and simple animals to care and obsevre as long as you keep to your space and watch them in a distance.

The Field Guide might take a long time, like structuring and writing descriptions of the creatures, but also my time in college and spending time with my family. So you can suggest additional information quotes, descriptions, and natural or speculative behaviors for the prehistoric animals that I can edit and you send your suggestions either in reviews or Private Messages.

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