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The newborn Tylosaurus They are so small that they fit on a person's hand. Here you can see (from left to right), the partial braincase, and a section of the upper jaw with tooth bases.
Credit: Christina Byrd, Paleontology Collections Manager at the Sternberg Museum of Natural History in Hays, Kansas
About 85 million years ago, when a vast sea covered Kansas, a wee, little sea monster died soon after it was born.
Despite its short life, this newborn, which is to be compared to the Giant was tall, is making waves today; a new analysis of its fossils reveals that it's the smallest Tylosaurus – a type of mosasaur, a fearsome marine reptile that lived during the dinosaur age – on record.
But it took a lot of years to identify this creature as a Tylosaurus. Paleontologists made the ID by examining tiny broken pieces of the dinosaur's snout, braincase and upper jaw, the only fossils of the animal they could find, a new study reports. [T-Rex of the Seas: A Mosasaur Gallery]
When the tiny leviathan's were found in the Smoky Hill Chalk Member of Western Kansas, in 1991, researchers thought it was a Platecarpus. This medium-sized genus of mosasaur had a short, rounded snout and could grow to almost 20 feet (6 meters) long.
But the new analysis revealed that the remains belonged to a much larger genus: TylosaurusTakuya Konishi, an assistant professor-educator in the Department of Biological Sciences at the University of Cincinnati. This monster of a mosasaur could grow up to 42 feet (13 m) in length, or nearly as long as a semitrailer.
<Img class = "img pure-lazy" big src = "https://img.purch.com/h/1400/aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzEwMi8xMDQvb3JpZ2luYWwvVHlsb3NhdXJ1cy1zaHV0dGVyc3RvY2suanBnPzE1MzkyOTA5MDk=" data-src = "https://img.purch.com/w/640 / aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzEwMi8xMDQvaTAyL1R5bG9zYXVydXMtc2h1dHRlcnN0b2NrLmpwZz8xNTM5MjkwOTA5 "alt =" An illustration of an adult Tylosaurus.”/>
An illustration of an adult Tylosaurus.
Credit: Shutterstock
It did not hurt that Konishi had done his dissertation on the Platecarpus, so he knew the beasts' anatomy inside and out. A few other clues indicated that the wee babe was a TylosaurusOne of the largest mosasaurs to swim in the Western Interior Seaway – a giant waterway that covered much of the U.S. Midwest and South from about 100 million to about 75 million years ago, Konishi told Live Science.
The biggest clue was the newborn's snout. Tea Tylosaurus is famous (at least among paleontologists) for its long snout, which is filled with sharp teeth, except for at the tip. Tylosaurus may have used this long, toothless tip as a battering ram to stun and wound prey, much like the orca whale (Orcinus orca) does today, Konishi said.
<Img class = "img pure-lazy" big src = "https://img.purch.com/h/1400/aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzEwMi8xMDUvb3JpZ2luYWwvVHlsb3NhdXJ1cy1zbm91dC5qcGc/MTUzOTI5MTAyOQ==" data-src = "https://img.purch.com/ w / 640 / aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzEwMi8xMDUvaTAyL1R5bG9zYXVydXMtc25vdXQuanBnPzE1MzkyOTEwMjk = "alt =" The genus Tylosaurus is known for its long snout (rostrum), which does not have any teeth at the upper tip. Curiously, the newborn Tylosaurus (right) barely has this feature, unlike the juvenile (left), which has been well-developed. “/>
The genus Tylosaurus is known for its long snout (rostrum), which does not have any teeth at the upper tip. Curiously, the newborn Tylosaurus (right) barely has this feature, unlike the juvenile (left), which has been well-developed.
Credit: Historical Biology
However, the baby mosasaur did not have a toothless, cone-shaped tip on its snout. An intensive analysis revealed that the creature had a teeny toothless portion on its snout. This indicates that Tylosaurus KONISHI said, but rather sprouted one between babyhood and adolescence.
In addition, the newborn's braincase Tylosaurus, has did the animal's slender teeth, the spacing and pattern of its tooth layout, and its quadrate – a question-mark-shaped bone at the back of the jaw that holds the jaw seal, Konishi said.
<Img class = "img pure-lazy" big src = "https://img.purch.com/h/1400/aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzEwMi8xMDYvb3JpZ2luYWwvVHlsb3NhdXJ1cy1iYWJ5LWFuZC1hZHVsdC5qcGc/MTUzOTI5MTEyMw==" data-src = "https://img.purch.com/ w / 640 / aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzEwMi8xMDYvaTAyL1R5bG9zYXVydXMtYmFieS1hbmQtYWR1bHQuanBnPzE1MzkyOTExMjM = "alt =" At nearly 4 feet (1.2 meters) long, this fully-formed Tylosaurus skull (bottom) is huge compared to the newborn's skull (gray inset). The white lines show corresponding parts on each skull, including the toothless tip (pink) and the toothy portion (purple).”/>
At nearly 4 feet (1.2 meters) long, this fully-formed Tylosaurus skull (bottom) is huge compared to the newborn's skull (gray inset). The white lines show corresponding parts on each skull, including the toothless tip (pink) and the toothy portion (purple).
Credit: Historical Biology
When it was alive, the babe's skull would have been measured about 7.2 feet (2.2 meters) long, making it about one-sixth the size of an adult, Konishi said. Mosasaurs boron live young (meaning these reptiles did not lay eggs), and the infant's small size suggests that it did not live long.
"I'm thinking that this came out and somehow, miraculously," Konishi said.
Despite the intensive analysis, however, Konishi and his colleagues could not determine the infant's species. There are two Tylosaurus known from that time and region – T. nepaeolicus and T. proriger – but without more-developed body parts, it's anyone's guessing which baby belongs to, Konishi said.
The study will be published online Friday (Oct. 11) in the Journal of Vertebrate Paleontology.
Originally published on Live Science.
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