Dinilysia
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Clade: Ophidia
Family: Dinilysiidae
Genus: Dinilysia
Type Species: Dinilysia patagonica meaning "terrible ilysia."
Described by Smith-Woodward, 1901.
Current Park Population: (7; all adults; 3 male, 4 female)
Park Diet: Thawed mice, rats, and eggs.
Natural Diet: Rodents, small reptiles, amphibians, and possibly baby dinosaurs.
Lifespan: 40 years
Habitat: Open Canyon Forests and Semi-Arid shrublands.
Native Ecosystem: South America and possibly North America. Anacleto Formation and possibly Hell Creek Formation, Montana, USA, 85-66 Million Years Ago, Early-Middle Campanian-Maastrichtian Stage.
Breeding Season: September-November
Gestation Period: Six to Eight weeks
Eggs Laid: 50-100 eggs
Hatching Time: Three-Five Weeks
Danger Level: 1 out of 10.
Summary: Snakes in the Fossil Record are often considered fragmentary, but there have been a handful of species. Dinilysia was a relatively large ambush predator, measuring approximately 2 m (6.6 ft) long. The skull morphology of Dinilysia is similar to boids, suggesting that it was able to consume large prey. Living in a desert-like environment, Dinilysia is likely a terrestrial or semi-fossorial animal.
Description: Their coloration is similar to Central African Rock Pythons or Ball Pythons, with light brown scales arranged in brown blotches joined in a broad, irregular stripe near the eye region, copper eyes, a pale underbelly, and the tail region had black stripes.
Diet: Dinilysia was a sit-and-wait ambush predator waiting for any small mammal, reptile, amphibian, and even a baby dinosaur to walk by. Dinilysia like most snakes like vipers, boas, and pythons have holes on their faces called pit organs, which contain a membrane that can detect infrared radiation from warm bodies up to one meter away. At night, the pit organs allow snakes to 'see' an image of their predator or prey as an infrared camera does, giving them a unique extra sense.
Physiology and lineage: The Dinilysia patagonica is a stem snake that is very closely related to the original ancestor of the clade of crown snakes. Once the fossil of the snake was discovered, an X-ray computed tomography was used to build a digitized endocast of its inner ear. The results displayed that the Dinilysia patagonica's inner ear anatomy had three main parts. It had a large spherical vestibule, large foramen ovale, and slender semicircular canals in its inner ear.
Especially significantly, the spherical vestibule is an inner ear organ that is a morphological signature of burrowing snakes. A sizeable spherical vestibule does not exist in aquatic or generalist (both land and water) snakes, only in snake species that burrow. A spherical vestibule contains a large saccular otolith, which transmits vibrations to the snake's brain. Due to a spherical vestibule, the Dinilysia patagonica was a species especially sensitive to low-frequency ground vibrations rather than airborne frequencies.
The surmounting evidence displays that Dinilysia patagonica was more than likely a terrestrial burrower from the Cretaceous era. This discovery also extends its evidence to the fact that a burrowing habit predates the lineages of modern snakes. These ancestral snakes detected predators and captured prey specifically using low-frequency ground vibrations.
Theories of origin: Dinilysia patagonica is one of the best-known Cretaceous, terrestrial snakes, native to the Late Cretaceous Anacleto Formation of Neuquen province, Argentina. The Dinilysia specimen has twenty-four mid-posterior trunk vertebrates. Dinilysia is referred to as such due to a variety of morphological features. The degree of knowledge represents the most valuable records of snakes from the Upper Cretaceous of Gondwana. Recently, Dinilysia has been labeled a sister group of all living alethinophidia. Therefore this Cretaceous snake still contributes a significant amount to the debate on the origin of snakes and phylogeny. In terms of the locality and age of the Dinilysia the fossils can typically be found in abundance in sandstone sediments favored to the Anacleto formation. Additionally, the overall morphological similarities between that of D. patagonica have been used to determine the phylogeny and possible relations of the characteristics which other more present snakes may share. The articulate snake vertebrate fossils were found and studied in terms of the trunks and vertebral morphological variation has allowed for the deduction that UNC-CIP 1 can be identified in the Dinilysia genus.
Additionally, an ongoing debate about whether snakes evolved on land or in the ocean; certain pieces of evidence point towards oceanic origin based on possible close relationships between snakes and mosasaurs. However, further evidence shows that terrestrial origin is quite possible because of the structural similarities between the inner ear of the Dinilysia and similar burrowing squamate snakes. Based on both the evolutionary and morphological features and similarities that D. patagonica possesses, evidence can be drawn from the features to predict the general location of origin. Furthermore, the anatomy of fossilized skull fragments of D. patagonica suggests that there are numerous plesiomorphic and apomorphic characters compared to respective extinct snakes and present-day snakes. These can be loosely attributed to the adaptive morphological characteristics present in the effects of terrestrial adaptation, in comparison to that of aquatic adaptation which would result in many more water adaptive features, especially in that of the skull and the spine as to ensure water to be a livable environment for the D. patagonica.
There are numerous resources for evidence of the morphological characteristics of D. patagonica, including a full medium-sized skull of D. patagonica which also has the posterior brain, the vessels, the cranial nerves, the inner ear, as well as the semicircular canals of the skull structure: which have all been naturally endocranially cast, which has been recorded as the first natural endocranial casting of an extinct snake species. The information that has been studied and presented from this fossil has brought light to new information regarding the morphological importance of different characteristics within the semicircular canals, as well as the functionality of the olfactory bulb. Through the study of the lightly differentiated castings of the portions of the brain, it was assumed that D. patagonica was a terrestrial reptile due to the level of development of the olfactory sensory bulb within the cast brain.[citation needed]
Therefore, if it had to be deduced whether snakes and more specifically, Dinilysia patagonica adapted terrestrially or aquatically, the presented studies all suggest in one form or another that the features and adaptations present in D. patagonica are more likely to be those of terrestrial adaptations than those of aquatic adaptations based on not only morphological characteristics but plesiomorphic and apomorphic shared characteristics to that of current living snake species.
Evolution: The biggest surprise was encountering the Dinilysia in Hell Creek, Montana these snakes aren't native as there are no fossils of their species in the Hell Creek Formation. One of the Keepers nicknamed A-LionGleek suggested to the research team hypothesizing the North American Dinilysia and the true South American Native Dinilysia had a common ancestor. He believes their ancestors were split apart from continental drift as North America and South America when Pangea broke apart at the end of the Triassic and by geographic isolation evolved into the snakes they are with similar characteristics and niches in their environment.
Interactions with other species: Dinilysia preyed on small animals and avoided the large predators in their native Anacleto Formation.
Normally the large herbivores of the Hell Creek Formation ignore the snakes although babies of young Leptoceratops, Thescelosaurus, Trierarchuncus, Pachycephalosaurus, Ornithomimus, Triceratops, Torosaurus, Edmontosaurus, Alamosaurus, Anzu, and Ankylosaurus aren't safe. Adult Thescelosaurus and Anzu would prey on Dinilysia.
There are some small animals Dinilysia potentially preyed on Trierarchuncus and Didelphodon which would have fought back.
The hatchlings of Acheroraptor, Pectinodon, Dromaeosaurus, and Tyrannosaurus would have been prey to Dinilysia although if given the chance and desperately hungry adults and adolescents preyed on Dinilysia
Extinction: Dinilysia in its native land would have become due to climate change altering its environment, lack of prey, and evolved efficient predators that outcompeted the snake. If it was still around 66 million years ago it would have been wiped out by the extinction event.
Danger Tip: This snake is a calm and passive animal although it's best not to get wrapped up by its coils and if provoked a bite from their sharp teeth in their jaws.
Significant Events: On the third day of the Team's First Rescue Mission while escaping a male T. Rex, Charlie Yeager meets a Female Dinilysia Snake and a Male Dromaeosaurus who are hiding from the Tyrannosaurus. The Male Dromaeosaurus runs out of the log prompting the T. Rex to chase the raptor as a distraction allowing Charlie and the Dinilysia to escape. Charlie stores the snake in a sack bag to later be taken to the park. On the final day, the team encounters a Slither of Dinilysia coiled up on top of a large log basking in the sun alongside other Hell Creek Reptiles and Small Mammals. They were scooped up in bags and taken to Paleo Park. They now live in the Hell Creek Building.
Hell Creek Building: The exhibit is a large terrarium with dense vegetation, small logs and sticks, flat rocks to bask, and loose soil allowing burrowing behavior. The Dinilysia can be viewed through thick glass windows.
Notable Individuals:
Kaa: A female Dinilysia named after the snake from The Jungle Book which Charlie Yeager encounters in the log, she now forms a bond with him.
Conclusion: Dinilysia represents how snakes are fragmentary in the fossil record and how animals like them and others Dromaeosaurus will sometimes turn up in places we don't expect they would live in that might seem impossible to us. Furthermore, Dinilysia does make slithering new members to Paleo Park.
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