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Hemiscylliusaurus

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Amongst the most widespread and numerous of Saurocene mosasaurs, Hemiscylliusaurus derives its name from modern carpet sharks of the genus Hemiscyllius, due to their roughly similar design, coloration, and habits.  Unlike their largely tropical chrondichthyan namesakes, these marine lizards can be found in coastal water essential worldwide, only avoiding the most frigid of seas.  This group has an excellent fossil record dating back to the late Oligocene, at which time they split from their pelagic relatives.  Several fossil genera have been named, including the enigmatic Densosaurus (possibly an abyssalsuchid) and the highly elongated Anguillasaurus from the late Oligocene to the early Pliocene, Siccusuchus with its numerous teeth from the Pliocene and Miocene, and the recently extinct possible herbivore Propriudon from the Pliocene and Pleistocene.  Hemiscylliusaurus itself appears to be a rather modest member of family in terms of its appearance, definite fossils are known from the late Miocene onwards.  A few subgenera have been proposed, mainly based on differences in dentition and lower jaw robustness, but genetics indicate these differences are not taxonomically restricted.

Over three dozen species of "Carpet Eel" have been described from habitats ranging from rocky sub-polar kelp forest to tropical reefs to mangrove swamps.  The largest species is the north Pacific Shaggy Carpet Eel (H. hirtus), which can grow to at least 3 meters in length.  The smallest species tend to be tropical reef dwellers that only grow to about 0.3 meters in length.  The name Carpet Eel is derived from two factors: their aforementioned resemblance to carpet sharks (and eels), and the fact that many members of the group often have extensive algal growth along their backs.  In some species, such as H. hirtus, these growths can be quite luxuriant and greatly obscure the outline of the animal when viewed from above.  In addition to serving as camouflage, a variety of fish and in particular crustaceans may be attracted by the plant growth, but will in turn be eaten by the mosasaur.

The short robust snouts of these mosasaurs contain some of the most complex teeth known to the group.  These are some of the few squamates that exhibit heterodont dentition, with the teeth toward the rear becoming increasing compressed, like blunt oval-shaped blades.  The more anterior teeth are the typical peg-like form one would expect a mosasaur to have, but even these are exceptionally blunt.  And finally, the palatal teeth of this genus are flattened with subtle grooves, not too dissimilar from mammalian molars or the dental batteries of hadrosaurs.  These adaptations show very clearly that Carpet Eels prey predominately on hard-shelled game such as crustaceans, snails, clams, urchins, and ammonites.  Even large polyped stony coral has been accepted by captive individuals!  Bottom-dwelling fish, squid, octopi, sea snakes, pipe lizards, carrion, and distasteful nudibranchs have also been recorded as prey items.  The remainder of Hemiscylliusaurus anatomy reflects their bottom-dwelling lifestyle.  Their elongate flexible bodies allow them to wriggle into cracks and crevices along the bottom in search of prey or shelter, while their strong snouts and powerful necks allow them to bulldoze through smaller obstructions.  The small pelvic flippers are exceptionally robust with most of the internal digits fused together; in conjunction with the tail, these enable them to brace themselves on the seafloor as the front end of the animal attempts to extricate a meal.  The flexible pectoral flippers are used to "crawl" along the bottom, amongst coral, or even over land for short distances.  Understandably, the latter activity is typically only engaged in by smaller species.  Like all mosasaurs, they posses a forked tongue which is readily used to sniff out prey.  Coloration is usually cryptic and the skin is composed of rough scales, larger on the top and decreasing in size ventrally.  Like in abyssalsuchids, Carpet Eels posses numerous grooves along their backs which encourage the growth of algae and other hitchhiking organisms.  Whether these structures evolved specifically for that purpose or for another is still debated.

Carpet Eels display reasonable levels of intelligence, at least on par with monitor lizards.  These mosasaurs are generally quite sluggish, spending most of their time resting on the bottom under ledges or in rocky lairs, but they can put on a surprising burst of speed when pestered, though not for very long.  Carpet Eels have been recorded holding their breath for over 2 hours, though anything longer than 30 minutes is unusual.  They are most vulnerable at the surface, so when in need of air they proceed as quickly as possible.  Known predators include sharks, large fish, other mosasaurs, aquaraptoriformes, large cephalopods, and birds of prey.  Mating is brief and violent, with the male biting the female behind the neck and much scuffling.  Pregnancy lasts between 4 and 7 months and the young, numbering between 6 and 20, are birthed in a shallow environment such as mangroves, tidepools, or shallow reefs.  The young are essentially miniature versions of the adults and will take anywhere from 6 to 18 months to mature.  Maximum lifespan remains undocumented, but may exceed 50 years in some of the larger species.  All of these figures vary by species.

Various species, both tropical and temperate, have proven exceptionally hardy in captivity and can even be prolific breeders.  Carpet Eels are not normally considered dangerous, but when provoked, they will bite and hold on with incredible force.  Large animals can easily shatter the bones of a human hand.  Carpet Eels are perhaps best known to the general public due to their accidental introduction to the Persian Gulf in 2280.  Apparently, a wealthy British entrepreneur paid to smuggle six H. elegans and four H. tesselatus into the modern world (details still under investigation) which he then housed in his small private aquarium in Dubai.  When he went bankrupt in 2280 he sold his aquarium, but not before paying some the keepers to secretly dispose of the Carpet Eels.  It appears that they were supposed to kill them, but misunderstood his directions and released them instead.  In 2282, an H. elegans specimen was caught by a trawling vessel in the region, and so the investigation began.  Fifteen H. elegans, four H. tesselatus, and one probable hybrid were captured by divers over the next five years and in 2290 Carpet Eels were officially declared eradicated.  Of course, this small breach in security was plenty of time to whip the global media into a frenzy of exaggerated claims and even spawned horror film.  The man in question denies having any knowledge of the animals' identities, claiming they were sold to him as "rare Australian eels"; he is still under investigation.  This marks the only occasion of a Saurocene tetrapod establishing a breeding population on modern Earth, short lived as it was.  There are an estimated 275 Carpet Eels still in captivity at qualified zoological institutions.

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Overview of Saurocene Mosasaur Diversity

Introduction to the Saurocene
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Comments8
anonymous's avatar
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Titanopetra's avatar
TitanopetraStudent Traditional Artist
Aww, I want one :D
ZoPteryx's avatar
ZoPteryxHobbyist General Artist
XD :)
asari13's avatar
asari13Hobbyist Traditional Artist
Cute
ZoPteryx's avatar
ZoPteryxHobbyist General Artist
Thanks!
Adamtheartist123's avatar
Adamtheartist123Hobbyist Traditional Artist
Awesome! Only if they existed in real life...
ZoPteryx's avatar
ZoPteryxHobbyist General Artist
Thanks!  Yeah, I'd love to have one as a pet! :D
Yutyrannus's avatar
YutyrannusHobbyist Writer
Hey you're back :D!

Looks great!
ZoPteryx's avatar
ZoPteryxHobbyist General Artist
Thank you! :)  Hopefully the remaining mosasaurs won't take quite as long! ;)
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