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.

Tarbosaurus: Beast of the Week

This week we will be checking out a huge tyrannosaurid.  Enter Tarbosaurus bataar!  Tarbosaurus was a large meat-eating dinosaur that lived in what is now Mongolia and China during the late Cretaceous Period, about 70 million years ago.  The largest known individuals infer that they could have been just a little smaller than the largest known Tyrannosaurus, at about 39 feet long from snout to tail.  The genus name translates to "Alarming Lizard".  When alive, Tarbosaurus would have shared its habitat with (and maybe hunted) fellow theropods, Deinocheirus and Therizinosaurus, as well as the hadrosaur, Saurolophus.

Tarbosaurus and young...and lunch life (except lunch...lunch is dead) reconstruction by me.

Tarbosaurus was an extremely large tyrannosaurid, second largest known, right behind Tyrannosaurus.  These two genus are very similar in appearance at first glance, but key differences are present.  In fact, the two may not be as closely related to each other as they each might be to other kinds of tyrannosaurids that are known.  Starting at the head, Tarbosaurus had a laterally slim head.  It's eye sockets were primarily facing sideways, so it wouldn't have had much depth perception.  Thanks to scans of the inside of Tarbosaurus' skull, and looking at the shape of the brain case, scientists can infer that Tarbosaurus would have had a great sense of smell and hearing, but it was lacking in the sight department.  It likely would have hunted relying on its sense of smell mostly, unlike T. rex, which had more forward-facing eyes.  Tarbosaurus' teeth were sharp and curved for crushing and tearing flesh and bone, but weren't as proportionally large.  The actual jaws were less flexible than those of most other tyrannosaurids.  It possessed two extremely short arms with two fingers on each hand.  The arms of Tarbosaurus are proportionally the tiniest out of all tyrannosaurids. (Yes, they were even smaller than T. rex's.)  When examined more closely, it was discovered that the arms of Tarbosaurus commonly endured stress factors, meaning they likely weren't completely useless in life.  Some have suggested they aided in taking down prey but personally I feel they may have had some role when it came to mating.  We may never know!

Tarbosaurus skeletal mount on display at the Cosmacaixa Museum in Barcelona, Spain.

There are a relatively large number of Tarbosaurus specimens on the fossil record.  Among these are small juveniles.  Thanks to these individuals, we know that Tarbosaurus was proportionally leggier when it was little, bulking up as it aged.  The teeth were also more blade-like, and less robust when they were young.  Tarbosaurus probably filled different ecological niches as it aged, preying on smaller, faster prey when it was younger, and moving on to bigger game as it matured.  In fact, thanks to bite marks on bones, we can be fairly certain that an adult Tarbosaurus was eating at least Deinocheirus, the giant, flat-billed, ornithomimid.

Juvenile Tarbosaurus skull

Lastly, we have actually found clues as to what Tarbosaurus' skin was like...well at least parts of it.  A large individual had a small patch of skin (sadly we don't know exactly where because it was messed with by fossil poachers) that shows small, round scales.  These scales are each only about two millimeters wide in diameter.  In addition, a Tarbosaurus footprint was discovered, that showed evidence of being scaly as well.  Because of this evidence, many folks tend to argue that Tarbosaurus and its close relatives wouldn't have had feathers in life.  This is flawed, however, since even modern birds possess similar textures on their own feet.  Plus, other fossilized non-avian dinosaurs have been unearthed with evidence of both scales and feathers on other parts of their bodies than the feet.

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

References

Currie, Philip J.; Badamgarav, Demchig; Koppelhus, Eva B. (2003). "The First Late Cretaceous Footprints from the Locality in the Gobi of Mongolia". Ichnos. 10: 1–12.

Hurum, Jørn H.; Sabath, Karol (2003). "Giant theropod dinosaurs from Asia and North America: Skulls of Tarbosaurus bataar and Tyrannosaurus rex compared" (PDF). Acta Palaeontologica Polonica. 48 (2): 161–190.

Rothschild, B., Tanke, D. H., and Ford, T. L., 2001, Theropod stress fractures and tendon avulsions as a clue to activity: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 331-336.

Saveliev, Sergei V.; Alifanov, Vladimir R. (2005). "A new study of the brain of the predatory dinosaur Tarbosaurus bataar (Theropoda, Tyrannosauridae)". Paleontological Journal. 41 (3): 281–289.

Tsuihiji, Takanobu; Watabe, Mahito; Tsogtbaatar, Khishigjav; Tsubamoto, Takehisa; Barsbold, Rinchen; Suzuki, Shigeru; Lee, Andrew H.; Ridgely, Ryan C.; Kawahara, Yasuhiro; Witmer, Lawrence M. (2011-05-01). "Cranial Osteology of a Juvenile Specimen of Tarbosaurus bataar (Theropoda, Tyrannosauridae) from the Nemegt Formation (Upper Cretaceous) of Bugin Tsav, Mongolia". Journal of Vertebrate Paleontology. 31 (3): 497–517.

Dinosaurs Among Us at the American Museum of Natural History

It's the day after Thanksgiving.  Many people cooked and ate a dinosaur last night.  This is nothing new.  I've been saying it for years.  Yet many people are still blindsided by the fact that birds are, in fact, literal dinosaurs.  (I just graded my tenth grade's vertebrate evolution quizzes...trust me.)  Finally, however, there is something that is available to ANYONE who happens to find themselves in New York City (at least until January) that not only educates, but shows proof of this amazing connection between modern birds around us and the most influential animals we never knew.  Let's go check out the American Museum of Natural History's best (I'm biased.) temporary exhibit, called Dinosaurs Among Us.

I had the privilege of being taken in as an explainer for this exhibit during the spring and summer of this year before I had to move out of New York.  When I first stepped in for the training walkthrough, the amount of sheer information was almost overwhelming, even for a museum.  Essentially this exhibit has a two main messages.  The first is to explain, on a broader sense, by using dinosaurs as the model, how evolution works.  The second is to bring home the fact that birds are dinosaurs, by the use of many awesome physical pieces of evidence, some of which have never been on public display before.

One of the life-sze Microraptor models hanging from the ceiling.  They have been painted glossy black-blue in accordance with the preserved melanosomes in their fossilized feathers.

When you first walk in you are greeted by life-sized life reconstructions of several of the keynote dinosaurs featured in the exhibit.  Most important is probably Citipati, due to the sheer amount of fossil material that has been found, and the fact that the American Museum of Natural History does a lot of field work in Mongolia, where this dinosaur was native to, and therefore has access to a lot of its fossils.  The largest and most dramatic model, however, is definitely Yutyrannus.  To my knowledge, a life-sized life reconstruction of this monster has never been made before this, and it looks great. Many of the life reconstructions actually feature real bird feathers, as well.

My first interaction with the Yutyrannus was a bit rocky.  We're cool now, though.

One key connection between birds and other dinosaurs is the act of nest building.  This exhibit features several spectacular fossils of nests and eggs that were laid by dinosaurs millions of years ago.  The manner in which these eggs were laid actually gives us clues as to just how closely related a species dinosaur mother was to her modern relatives.

Life-size replica of a Gigantoraptor nest on display in Dinosaurs Among Us.  Yes, you're allowed to stand in it.

One very interesting way to tell is whether or not the eggs in a dinosaur's nest were laid in pairs.  Check out this replica of a Gigantoraptor's nest above.  See how the eggs are spaced in twos?  That means that the mother of these eggs had two functioning ovaries, and was producing an egg from each of them.  This is in contrast to nests like...

This, laid by a troodontid, called Byronosaurus.  The eggs aren't arranged in pairs.  This looks more similar to a clutch of eggs laid by a modern bird.  This is because modern birds only have one functional ovary, and therefore only lay one egg at a time, resulting in this arrangement.  (Fun fact: They have two ovaries as an embryo, but lose one as they develop.  This tells us that they evolved from dinosaur ancestors with two.) We used to think this was an adaptation for lightness so they could fly...but here are some non-avian dinosaurs that didn't fly...and went extinct that way.

Telling you just how close a particular non-avian dinosaur is related to modern birds is a constant theme throughout this exhibit.  In fact, under each specimen, there is a tiny infograph, modeled after a barometer, with the needle pointing somewhere between the earliest ancestral dinosaur and modern birds.

Dino-Bird-o-meters are all over this exhibit.  In this case, it is telling us that Yutyrannus, a tyrannosauroid, is more closely related to modern birds than it is to many other kinds of dinosaurs.

After eggs and nests the exhibit looks at the actual anatomy of different dinosaurs, especially the bones.  As with single ovaries, hollow bones was another feature we used to think birds evolved specifically for flight.  Since then we have learned that this was also not the case.  Large dinosaurs, like Allosaurus, demonstrated here, and even gigantic sauropods, had hollow bones.  We now think this was a sign of having a more efficient one-way respiratory system that birds retain today.  When a bird breathes air into its lungs, it doesn't simply get exhaled out the same way it went in.  It goes into more chambers throughout the body, including ones connected to hollow cavities in the bones.  Birds today use it to help them fly better, most likely, but prehistoric dinosaurs probably used it for other reasons, like getting oxygen throughout their huge bodies more efficiently.  We have also found similar respiratory systems in modern crocodilians and even some kinds of lizards so...yea definitely not a specific flight adaptation.

This is a broken piece of an Allosaurus leg bone,displayed next to the bone of a modern bird.  The hollow inside has since been fossilized with a different mineral from the actual bone.

Having fused clavicles, or a wishbone, was another feature previously thought to be exclusive to birds...until it started popping up in the fossil record in dinosaurs like Velociraptor.  This exhibit has an awesome articulated Velociraptor specimen on display with the wishbone clearly visible.

Beautifully articulated Velociraptor specimen.  You can see the shallow v-shaped clavicle at the base of the neck.

My favorite specimen in this exhibit would be the Tyrannosaurus wishbone, however.  That's right, T. rex had a wishbone, just like that turkey you ate.  To drive the point home even harder, it is displayed in a case surrounded by the wishbones of various modern birds.

T. rex wishbone.  My favorite piece in the exhibit.

Finally the exhibit goes from internal anatomy, like bones, to external anatomy, like skin and feathers. A myriad of specimens showcasing visible preserved feathers on fossilized bodies is showcased here from the curious quill-like structures of Tianyulong...

Tianyulong cast on display, complete with bristles on the back.

To the extremely feathered, Confuciusornis, in all its plumed glory.

Confuciusornis.  Just one of many feathered specimens on display at Dinosaurs Among Us.

At the end of this exhibit, a common question we receive from guests is "So what defines a bird?" This is a great question.  Yes, birds are dinosuars...but not all dinosaurs were necessarily birds, of course.  It's like saying a Ferrari is a car, but the car I drove to New Jersey to see my family today sure as heck wasn't one!  So what they are really asking is where in the fossil record do we draw the line between birds and non-avian dinosaurs?  What combination of features can we confidently say that all birds must have to be considered a bird?

Archaeopteryx fossil.  For a long time this was the only feathered fossil known to science.  Because of that, Archaeopteryx was referred to as the "first bird" when in reality the line between "bird" and "other dinosaurs" is too blurred determine where one stops and the other begins.

The answer to this is as frustrating as it is beautiful; We don't know!  And to put it bluntly...we shouldn't really care.  Nature has nothing to do with which label we put on which organism.  They evolve to survive and the process just is what it is.  Labeling something a bird based on an anatomical milestone just can't flow with what actually happens.  The amazing side of this seemingly frustrating coin is that this means that the fossil record for non-avian dinosaurs to birds is rich with plenty of specimens to learn from for years to come.  This is in harsh contrast to as little as a few decades ago when all we had to work with as far as feathered, birdlike dinosaurs were concerned, was good old Archaeopteryx, once considered "the first bird" and now just one of many feathered, birdlike dinosaurs.

If you have an interest in paleontology, birds, or nature in general PLEASE visit this exhibit if you have not already.  The American Museum of Natural History has been a prominent part of my life since I was born.  I've seen lots of fantastic temporary exhibits come and go.  That being said, this exhibit blew me away.  I purposely didn't write about and include photos of everything in there.  In fact, I only showed you a smaller portion of what this exhibit has to offer to further encourage you to go out and see it in person for yourself.   

Gorgonops: Beast of the Week

This week we will be checking out a prehistoric beast with an even beastlier name!  Let's look at Gorgonops!  Gorgonops was a creature that lived in what is now Southern Africa during the late Permian era, between 260 and 254 million years ago.  It was a synapsid, which means it belonged to the same group as mammals, yet it also shared characteristics with animals we consider reptiles. Because of this, Gorgonops and its close relatives are also informally referred to as "mammal-like reptiles".  The much more famous, Dimetrodon, is an earlier example of a synapsid that is also a "mammal-like reptile"s.  The largest Gorgonops measured about six feet long from snout to tail and would have eaten meat when alive.  Within the genus, there are a few species of Gorgonops recognized by science.  Gorgonops torvus was the first to be discovered and is probably the most well-understood because multiple specimens of it have been found.  Gorgonops whaitsi was larger than G. torvus and had a more robust snout.

Gorgonops whaitsi life reconstruction by Christopher DiPiazza.

Gorgonops' genus name translates to "gorgon face" in reference to the gorgon, a monster from Greek mythology that resembled a woman with snakes for hair.  According to the legend, looking directly at a gorgon's face would turn a person to stone.  (Medusa was the most famous gorgon.)  In contrast to this, Gorgonops possessed extremely long, sharp teeth in the front of it's mouth, which gave its skull a particularly menacing look.  Because of this, it was named in honor of the mythical creature.  It is unlikely that looking at an actual Gorgonops would turn anyone to stone, however, and snakes wouldn't evolve for tens of millions of years after Gorgonops' time.

Kinda like that...but not.

The first Gorgonops was discovered and named during the 1800s by a man named Richard Owen. (Somewhat Unrelated Fun Fact: Mr. Owen also coined the term "dinosaur")  Since then, several other kinds of related animals from the same family have been unearthed.  Since Gorgonops was the first, the name of this family is known as gorgonopsidae.

Gorgonops whaitsi skull from the American Museum of Natural History

Gorgonops is most well-known for its teeth, which, like I said earlier, were proportionally long, sharp, and curved.  They were similar in appearance to the canines on some carnivorous mammals, and because of their sheer length they are often compared to saber-tooth cats, despite the fact that gorgonopsids and cats aren't actually directly related beyond both being synapsids.  In addition to the two, downward-facing saber teeth, Gorgonops also possessed shorter teeth for nipping in the front of its face and shorter, broader teeth just behind the sabers, probably for cutting.  It is likely that Gorgonops delivered a killing bite to prey with the long teeth, puncturing vital areas, like the neck.  Then it would use other teeth to actually strip the meat off the carcass.  It is also very possible the long teeth had a role to play within the species, possibly for display.  This possibility would hinge on whether or not the teeth of gorgonpsids were visible or covered in some kind of soft tissue in life.

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

References

Gebauer, E.V.I. (2007). Phylogeny and evolution of the Gorgonopsia with a special reference to the skull and skeleton of GPIT/RE/7113 ('Aelurognathus?' parringtoni) (PDF) (Ph.D. thesis). Tübingen: Eberhard-Karls Universität Tübingen. pp. 1–316.

Jacobs, L. L., Winkler, D. A., Newman, K. D., Gomani, E. M. & Deino, A., 2005, Therapsids from the Permian Chiweta Beds and the age of the Karoo Supergroup in Malawi. Palaeontologia Electronica. Vol. 8, #1, pp. 28A: 21-23

Megaraptor: Prehistoric Beast of the Week

Lets check out the impressive, yet mysterious predatory dinosaur, Megaraptor namunhuaiquii!  This dinosaur lived in what is now Argentina during the Cretaceous Period, roughly 90 million years ago.  Even though only parts of its skeleton have been found, Megaraptor is estimated to have been a little under thirty feet long from snout to tail. 

My Megaraptor namunhuaiquii life reconstruction.  If it was an allosauroid, it may have had feathers like I have shown.  On the other hand if it was, indeed, a tyrannosauroid, it almost certainly had feathers like I have shown.  So feathers was the safer choice with this one.

Megaraptor started out only being known from very scant remains, and has gradually become closer to being more completely known over the years since its discovery.  Initially only one of its gigantic sickle-shaped claws was discovered.  Upon seeing this, most scientists assumed it was the second toe claw of a dromaeosaur, much like Velociraptor or Deinonychus, just a heck of a lot bigger.  In fact, it would have been the biggest dromaeosaur known if that was the case, so it was named Megaraptor which translates to "Giant Thief/Hunter".  The claw, itself, was just under a foot long!

Years later a few more bits and pieces were found from this dinosaur including some of the arm and hand.  In addition, a dinosaur, named Australovenator, was discovered, which bore striking similarities to the known parts of Megaraptor.  Because of this, it was determined that the monster claw did not belong on the foot but on the first digit of the hand which is what Australovenator had.  Megaraptor wasn't a dromaeosaur at all. Instead, it may have been from the same group of theropods that includes Allosaurus. Even amongst other large theropods, many of which had enlarged first claws on their hands, like Baryonyx (name actually translates to "heavy claw"), the claw of Megaraptor was proportionally the largest. 

One of Megaraptor's hand claws.  If it were to give you a wedgie, you'd die.

But there's more!  In 2014 even more material from Megaraptor was discovered.  A juvenile specimen preserved even more bones, including part of the skull.  We now know that at least as juveniles, Megaraptor would have had very long, low snouts, with proportionally small teeth.  The teeth themselves curved towards the back of the mouth.  It is because of the teeth that some paleontologists propose Megaraptor wasn't an allosauroid either, but rather a kind of tyrannosauroid, similar to Eotyrannus or Dryptosaurus. (which also possessed huge hand claws)

Section of the upper jaw of a juvenile Megaraptor.  Image from Porfiri et al. 2014.

So which is it?  What was Megaraptor!?  The definite answer to that is...we don't know.  We have some choices!  But we don't know anything for sure for now.  And that's okay!  This happens a lot in paleontology.  In some ways it is the unsolved mysteries and multiple possible truths and different ideas put forth by different individuals that make this field so much fun. 

That's all for this week!  As always feel free to comment below or on the facebook page! 

References

Benson, R.B.J., Carrano, M.T., Brusatte, S.L., 2010. A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic. Naturwissenschaften 97, 71-78.

Calvo, J. O.; Porfiri, J.D.; Veralli, C.; Novas, F.E.; Poblete, F. (2004). "Phylogenetic status of Megaraptor namunhuaiquii Novas based on a new specimen from Neuquén, Patagonia, Argentina". Ameghiniana 41: 565–575.

Novas, F.E. (1998). "Megaraptor namunhuaiquii, gen. et sp. nov., a large-clawed, Late Cretaceous theropod from Patagonia". Journal of Vertebrate Paleontology 18: 4–9.

Porfiri, J. D., Novas, F. E., Calvo, J. O., Agnolín, F. L., Ezcurra, M. D. & Cerda, I. A. 2014. Juvenile specimen of Megaraptor (Dinosauria, Theropoda) sheds light about tyrannosauroid radiation. Cretaceous Research 51: 35-55.

Machairoceratops: Beast of the Week

This week we will be looking at another recently discovered horned dinosaur.  Enter Machairoceratops cronusi!

Machairoceratops was a ceratopsian dinosaur, which means it was in the same group as the more famous, Triceratops.  Within this group, however, it was more closely related to Diabloceratops and Nasutoceratops.  Machairocearatops' name translates to "Bent Knife Horned Face".  This is in reference to the shape of the two horns that grew from the top of the dinosaur's frill.  The species name, "cronusi" is after the mythical Greek god, Cronus, who cut off his dad's testicles with a curved sword.  (Next time you think your family has drama, remember that.)  In life, Machairoceratops would have been a plant-eater.  It lived in what is now Utah, USA, during the Cretaceous period, about 77 million years ago.  From beak to tail it would have measured about twenty feet long based on the skull. (Only the skull was found.)

Two rival Machairoceratops use their horns to lock into one another as they engage in a shoving match.

Like its relatives, Machairoceratops had a beak, a frill behind its head, and horns...very unique horns.  I know I say "unique" a lot in reference to ceratopsians, but it holds true!  Especially when it comes to this genus.  The two horns on the top of the frill curve forward and downward.  Frill horns aren't unheard of ceratopsians...but this exact orientation and curvature combined with their length, is.  It also had one horn over each eye which curved slightly upwards.  Due to the fragmentary remains of the skull, we sadly don't know what kind of horn ornamentation Machairoceratops had over its snout, if any at all.

Known fossil material from Machairoceratop's skull.  Image is from the paper by Eric K. Lund, Patrick M. O’Connor, Mark A. Loewen, Zubair A. Jinnah, referenced below.

As is the case with all ceratopsians, we don't know exactly why Machairoceratops' horns and frill evolved the way they did.  But it is very likely it had something to do with interacting with other members of its species.  If ceratopsian horns and frills were purely for defense against predators, they would likely be more uniform from species to species.  But this isn't the case.  Typically, when a variety of different, but related animals have the same sort of trait that is unique in form to each species, it has to do with some sort of intraspecies communication, like sexual display.  Just look at modern songbirds and their variety of colors and calls, or ungulates and their horns/antlers as modern comparisons. When it came to Machairoceratops, I felt that the overall shape that the brow and frill horns made together looked like it might serve well for combating rivals in head-to-head pushing behavior.  The antlers of modern reindeer also form this forward-facing crescent form, and they use them similarly.  Can I prove this was exactly how Machairoceratops used its horns?  Of course not.  But it's possible and also fun to think about.

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

References

Eric K. Lund, Patrick M. O’Connor, Mark A. Loewen and Zubair A. Jinnah (2016). "A New Centrosaurine Ceratopsid, Machairoceratops cronusi gen et sp. nov., from the Upper Sand Member of the Wahweap Formation (Middle Campanian), Southern Utah". PLoS ONE. 11 (5): e0154403.

 

Palaeosaniwa: Beast of the Week

This week we shall be checking out a prehistoric reptile whose lineage continues to this day.  Enter Palaeosaniwa canadensis.

Palaeosaniwa was a lizard that lived in what is now North America, including Alberta, Canada, and Wyoming and Montana, USA, during the Late Cretaceous Period, from 75 all the way to 66 million years ago.  Within this time there may have been multiple species within the genus, but canadensis is the most well known.  Palaeosaniwa was a relatively large lizard, capable of growing to over eleven feet long from snout to tail, judging by the remains of it that have been found.  The genus name translates to "Ancient Saniwa".  Saniwa being another, slightly younger by a few million years, but still very much prehistoric, kind of lizard.  When alive, this Palaeosaniwa would have been a meat-eater.

Palaeosaniwa getting chased by an angry Anatotitan.

Palaeosaniwa was a kind of veranoid lizard, in the same family that includes living monitors, like the Komodo Dragon, as well as the extinct marine lizards, the mosasaurs.  Like the modern Komodo Dragon, Palaeosawina had long, curved, serrated teeth which were probably adept at grabbing and tearing mouthfuls of meat off carcasses.  It likely had other adaptations in common with its modern relative, but unfortunately venomous saliva and forked tongues have never fossilized.

Me comforting my modern varanoid friend, Bruno, the Black-Throat Monitor (Varanus albigularis ionidesi)  He would have been way too emotionally sensitive to survive the Cretaceous.

There is something to be respected about a lizard that lived for such a long span of time amongst dinosaurs.  Despite the fact that an eleven-foot lizard is nothing to scoff at, it still coexisted with some of the largest and potentially dangerous dinosaurs of all time.  Veranoids historically tend to be very adaptable.  Their strong arms and legs, each ending in five curved claws are great for climbing, digging, and running.  Their long muscular tails are an effective weapon against enemies and also allow them to be strong swimmers.  This combination of adaptations would have made this lizard a jack-of all trades, opportunistic meat-eater, a very good place to be in the long run.  Because Palaeosawina was a mid-to-small scale meat-eater, pretty much every other creature in its community probably had some sort of beef with it.  Large plant-eaters like ceratopsians and hadrosaurs likely would have seen it as a threat to their eggs and babies and may have tried to chase or even kill it if spotted, while large predators like tyrannosaurids would have likely hunted it for food in addition killing it to protect young.  Despite this, this lizard still managed to carve a prominent niche that remains intact to this day thanks to its modern kin.  Palaeosawina would have had to be an extremely tough lizard!

That's all for this week.  As always feel free to comment below or on the facebook page.

References

Archibald, J. David (2011). Extinction and Radiation: How the Fall of Dinosaurs Led to the Rise of Mammals. JHU Press. p. 43.

Michael Joseph Balsai, The phylogenetic position of Palaeosaniwa and the early evolution of the Platynotan (Varanoid) anguimorphs (January 1, 2001). Univ. of Pennsylvania - Electronic Dissertations. Paper AAI3031637.