I don’t know why I’m fond of Tylosaurus. It feels as natural as falling into the water. I’m sure the paleomedia of my youth had a significant effect.

Of course I knew the importance of Mosasaurus to the history of paleontology, a critical early find that demonstrated there were once whale-sized reptiles in the seas, but it was Tylosaurus that seemed fiercest of all. Charles R. Knight brought the lizard to life in evocative art, the sinuous reptile chasing fish through the ancient seas. The Land That Time Forgot made the menace real on broadcast tv matinee movies, the carnivore among the first to menace the crew of the German U-Boat that surfaces in Caprona.

So you can imagine my excitement that we now have a new Tylosaurus, and it’s a big one.

Paleontologist Amelia Zietlow and colleagues announced the new marine reptile yesterday. Up until now, the largest Tylosaurus specimens were thought to belong to the iconic, original species Tylosaurus proriger named in 1869. Estimates of how large they could grow sometimes exceeded 50 feet. But Zietlow and colleagues noticed that the very biggest Tylosaurus specimens, which stretched up to a slightly more modest 43 feet when reconstructed, were different from the classic proriger. The largest specimens are now known as Tylosaurus rex.

T. rex - the actual tyrant lizard, not the dinosaur - swam in a warm inland sea around 80 million years ago, over what’s now Texas. Aside from the known specimens being significantly larger than adult T. proriger fossils, the new Tylosaurus species has finely-serrated teeth that would have helped each crown slide more easily through the touch skin of turtles, sharks, and other marine reptiles. You can have a look for yourself at multiple museums. The Tylosaurus on display at the Perot Museum of Nature and Science in Dallas, “Bunker” the Tylosaurus at the University of Kansas in Lawrence, and “Sophie” swimming over the heads of visitors at the Yale Peabody Museum in New Haven are all Tylosaurus rex.

The new study does more than establish a new name and identity for a charismatic carnivore. When paleontologists find a new fossil and give it a species assignment - either as a member of a known species or a new one - they are making a judgment call. Sometimes what seems like a new species is a different age group of something familiar, or even a more complete example that had previously been known from fragments. But sometimes fossil specimens are lumped into existing species when they are really something new, their subtle differences not due to age but because they are part of a different evolutionary twig on the larger branch of their family. This is what happened with Tylosaurus rex, its skeletal differences attributable to being a unique species rather than variation among T. proriger fossils.

The researchers have already identified other new potential species. In the new mosasaur family tree, the paleontologists found that Tylosaurus rex was a close relative of Tylosaurus proriger. But both are close to another large mosasaur genus called Hainosaurus. Some specimens previously called Tylosaurus are clustered among the Hainosaurus species on the basis of their shared characteristics. The implications of these shifts are beyond the scope of the new paper, but they indicate a direction for future research. The Tylosaurus specimens popping up where they weren’t expected could signal that they belonged to existing Hainosaurus species - or they could be entirely new. Either way, chances are very good that we’re going to be getting more mosasaurs in the near future, a rewrite of just how many species of immense, toothy reptiles were swimming the world’s coasts as tyrannosaurs stalked the land.

Scribblings

• I commissioned the amazing artist Emma LeRae to create a poster and a sticker for my forthcoming book Tyrant Lizard Queen. Aren’t they gorgeous? I’ll be selling these at events and online as publication approaches, but, if you want to get one right now, Emma’s got both up for sale on her website. Throw her some bucks and get some amazing, original paleoart.

  

• Would you still love me if I wrote about worms? For Sierra, I shared a few thoughts about the underappreciated burrowers living beneath our feet.

• Baby sharks are sensitive to oncoming storms. What tips them off that it’s a good time to head for deeper water? Last week’s new article, now on my blog.

• More than 70 years ago, paleontologists uncovered the skeleton of a plesiosaur with a tooth embedded in one of its neck bones. That tooth, we now know, belonged to the giant fish Xiphactinus - a tarpon-like predator that bit the marine reptile in the neck. I’ve got the story for premium subscribers.

• I like the new Walking With Dinosaurs. I do. But episode five felt like a retread of the 2013 Walking With Dinosaurs movie, its storytelling feeling thin and repetitive. The latest entry in I Want My DinoTV for premium subscribers.

Stomping to a City Near You

• SoCal friends, I’ll be speaking at the San Bernardino County Museum on June 11th! I’ll be talking about my book When the Earth Was Green, taking the audience on a journey back to the forests that made us. Details at the museum website.

• On July 28th I’ll be joining the Snug Books nonfiction club to talk about When the Earth Was Green. You can grab tickets for the event here.

Ear Perks

• HOPE looks like run-and-gun action mixed with creature movies like A Quiet Place and Arcadian. The horseback sequence alone is something I’m going to have to see.

• Doug Jones is an iconic actor. No one else embodies creature characters quite like him, whether it’s in The Shape of Water, What We Do in the Shadows, Hocus Pocus, or the dozens of other projects he’s been involved with. I’m so excited he’s getting his own documentary.

• I’ve been listening to Hailey Piper’s Queen of Teeth and it’s one of my favorite books this year. It belongs on the shelf next to Spread Me, The Woods All Black, and Walking Practice, proving once again queer people do body horror best.

And finally, Kazoo the kitten is settling in very well. She’s asleep on my desk next to me as I type this, no doubt recharging to run full tilt across the house the rest of the day. Now and then I’ll hear a squeak because she wants to come up and be close.