Shonisaurus: Beast of the Week

This week we will be looking a HUGE seabeast!  Make way for Shonisaurus popularis!  Shonisaurus was an ichthyosaur, in the same group as the more famous, Ichthyosaurus.  Like it's relatives, Shonisaurus' body was shaped similarly to that of a fish, despite the fact that it was an air-breathing reptile.  (This evolutionary strategy would pop up again, millions of years later with mammals in the form of whales.) Shonisaurus stands out because it was so large, measuring about 50 feet from snout to tail as an adult.  It lived in the ocean that covered what is now Nevada, in the USA, during the late Triassic Period, about 215 million years ago.  The name, Shonisaurus, translates to "Shoshone Mountain Lizard" in reference to the mountains in which it was found.  When alive, Shonisaurus would have eaten mollusks and fish.

Shonisaurus was an earlier form of ichthyosaur, so it did not possess all of the telltale characteristics you might see in later, more famous kinds, like Icthyosaurus.  For one thing, Shonisaurus presents no evidence of having possessed a dorsal flipper when alive, nor a full tail fluke.  So it wouldn't have had the distinct tuna-like profile other, later ichthyosaurs had.  Its lower flippers, that had evolved from walking limbs of its ancestors, were relatively long and narrow, while later relatives had more rounded ones.  One feature it had that did pass on to the rest of the ichthyosaur group was the fact that it had exceptionally large eyes, even proportional to its immense body size.  This suggests that Shonisaurus could see where there was little light, and may have spent at least part of its time in very deep waters.

Shonisaurus skull cast on display at the 2015 "Mega Dinosaur Exhibition" in Tokyo, Japan.

Shonisaurus was large.  It was one of the largest marine reptiles known to science, in fact.  So what and how did it eat?  Well, luckily, along with over thirty adult skeletons on the fossil record of this beast, paleontologists have also identified coprolites (fossilized poop) from it.  Turns out, according to the poop, Shonisaurus was eating squid, belemnites (like a squid but with an internal shell) and soft fish.  Interestingly enough, however, these prey items were all small, so it means that Shonisaurus must have been devouring huge quantities of them in order to grow and stay alive.  In order to better understand this, we can take a look at modern marine giants that prey on small animals.  Balene whales come to mind first, but as their description suggests, they had balene, an adaptation that helps them devour krill and other small prey in a very specific fashion.  Shonisaurus had small, almost nonexistent teeth that faced somewhat sideways in the mouth.  In fact, it appears that Shonisuarus' lineage was on its way to doing away with teeth altogether. (Which makes sense since there are many kinds of later ichthyosaurs that were toothless.)  I feel an even better modern analogue than whales would be the Basking Shark and Whale Shark.  These two kinds of sharks, in addition to also being very large, have no teeth in their mouths, but they can open them extremely wide as they filter feed on small prey.   Having been a reptile, Shonisaurus would have been able to open it's jaws relatively wide, as well, and could probably achieve similar feeding feats.

That is all for this week!  As always feel free to comment below or on our facebook page!

References

Kosch, Bradley F. (1990). "A revision of the skeletal reconstruction of Shonisaurus popularis (Reptilia: Ichthyosauria)". Journal of Vertebrate Paleontology. 10 (4): 512–514.

Mcmenamin, Mark A.s., Meghan C. Hussey, and Lydia Orr. "Ichthyosaur Coprolite With Nautiloid: New Data On The Diet Of Shonisaurus." (2016): n. pag. Web.

Nicholls, Elizabeth L.; Manabe, Makoto (2004). "Giant Ichthyosaurs of the Triassic—A New Species of Shonisaurus from the Pardonet Formation (Norian: Late Triassic) of British Columbia". Journal of Vertebrate Paleontology. 24 (4): 838–849.

Mongolian Paleo Drama: Year in the Making

When I paint life reconstructions.  Unknown to the viewers, there is almost always a story behind every painting.  There are usually never any hints, or givaways, or any sign of a bigger picture, but as I'm working on the piece, I try to think of what that particular dinosaur or other prehistoric creature has gone through up until the exact second in time that I choose to capture it's image, as well as what might happen to it after that second is over.  In fact, if you were to ask most artists, they will probably tell you the same thing.  If you turn on Netflix and check out Bob Ross, you will see that he is a prime example of this, narrating his own story as he works along through his piece.  I strongly feel like if it wasn't for the artist's imagination and ideas behind the paintings, the products, themselves wouldn't have as much life.

That penguin, for instance...he's gonna make it.  He just is.

Well, sometimes I do give hints as to what is about to happen, or happened in the past of my subjects.  In the case that I'm about to show you, most people wouldn't have noticed there was a bigger story, because the two paintings in question were painted, and therefore shared with the world a year apart from one another.  But they are connected.  Let's look at the first one below.

It's my Therizinosaurus, a plant-eating theropod that lived in what is now Mongolia.  I was inspired by sloths while painting this fellow.  Back when I was working at zoos, I witnessed one of our male sloths, Eugene, fall asleep with a piece of lettuce in his hand.  Minutes later he woke up from his spontaneous nap to continue feasting.  I thought it would be cute to show a dinosaur doing something similar.  However, falling asleep can be dangerous, especially if you have predators...

Jump forward in time one year to November of 2016 when I finished this painting of a mother Tarbosaurus feeding her young.  Tarbosaurus was also from Mongolia and would have coexisted, and possibly hunted Therizinosaurus.  Now look closer at what exactly it is that she's feeding her baby...

That's right.  The hunk of meat that is being fed to her baby is the disembodied arm of Therizinosaurus, who likely was ambushed by the tyrannosaurid during his nap.  But there's a twist here.  Look closely at the mother Tarbosaurus again.  Not all that blood is coming from the disembodied arm.

Therizinosaurus managed to get a few hits in with his enormous claws before he was killed.  One nice slash to the face and another, deeper stab, to his attacker's neck and shoulder.  This Tarbosaurus is bleeding, and judging by the second wound, she might not have much time left.  Let's hope her baby can learn to hunt on his own quickly!

Belonostomus: Beast of the Week

Today we will be checking out an often unfairly overlooked prehistoric fish.  Enter Belonostomus!  Belonostomus was a ray-finned, or bony fish, that lived in many parts of North America and Europe through much of the the Mesozoic Era.  It was wildly successful, the oldest species of this genus are from the Jurassic, about 150 million years old, and the youngest to date are all the way past the end of the Cretaceous, into the earliest part of the Paleocene, 59 million years ago!  Belonostomus on average tend to hover between a foot to almost two feet long from snout to tail, depending on the individual and species, of course.  On the other end of the size spectrum, there are Belonostomus specimens that are only about an inch long, which may have been adults.  (Unfortunately their skulls were too damaged to identify if they were, in fact adults or juveniles at the time of their deaths.)  The name, Belonostomus, translates to "Big Long Mouth" because...well, look at its mouth!

My life reconstruction of a still unnamed species of Belonostomus.  This painting was commissioned by Nathan VanVranken and featured with his recent research, presented at the 2016 Society of Vertebrate Paleontology meeting.

When alive, Belonostomus would have been a meat-eater, probably using its long, thin snout, lined with small, pointed teeth to shred smaller fish and other aquatic prey.  Its long, streamlined body, which was a characteristic of a fast-swimmer, also probably aided it in hunting.  Being medium-sized for a fish, it also probably had to worry about getting eaten by larger predators from both the water, like larger fish and marine reptiles, the air, in the form of pterosaurs, and probably even dinosaurs, like Baryonyx.

Belonostomus muensteri specimen on display at the Museum für Naturkunde in Berlin, Germany.

Modern Needlefish, which share a family with Belonostomus, look similar in many ways to their prehistoric relatives, and provide a decent modern analogue when imagining what Belonostomus might have been like when alive.

Close up of the teeth and jaws of Belonostomus sp featured in Van Vranken's 2016 research.

What is interesting about Belonostomus, is the fact that it is known from several really well preserved fossils, that range greatly in time, as stated above.  In fact, we can tell a lot about how both marine, and freshwater ecosystems were forming thanks to the presence of Belonostomus fossils.  And, yes, it is likely that Belonostomus could be either a fresh or salt-water fish, depending on the exact species.

References

Kogan, Ilja, and Martin Licht. "Erratum To: A Belonostomus Tenuirostris (Actinopterygii: Aspidorhynchidae) from the Late Jurassic of Kelheim (southern Germany) Preserved with Its Last Meal." Paläontologische Zeitschrift 89.3 (2014): 671. Web.

Van Vranken, N., Fielitz, C. BRIDGING THE GAP: THE BIOSTRATIGRAPHIC RECORD OF THE GENUS BELONOSTOMUS WITH NOTES ON NEW OCCURENCES IN TEXAS AND MEXICO. : Journal of Vertebrate Paleontology, Program and Abstracts, 2016. 242pp.

Woodward, Arthur Smith. "Genus BELONOSTOMUS, Agassiz." The Fossil Fishes of the English Wealden and Purbeck Formations (n.d.): 100-01. Web.