Sunday, December 9, 2018

Volgatitan simbirskiensis

Titanosaurs AGAIN?!
Well, a new titanosaur has just been described, and after much searching, I seem to have made the first skeletal diagram of it. It seems to be about the same size as Mendozasaurus, which I used to restore it here. With only 7 caudals to its name, scaling was tricky, but with the position of the first caudal as Ca1, scaling went smoother (and shrank down that Dreadnoughtus-sized beast that I had before). After much shuffling of vertebral orientations, this skeletal was completed, taking only two days to finish.

In addition to being a rather important titanosaur (the paper title's pretty self-explanatory), this is a milestone in my skeletal drawing history: this is my first skeletal that depicts a taxon that is NOT from South America (okay, I did make a bad Megalosaurus and a really bad Carcharodontosaurus first, but this is my first SUCCESSFUL skeletal depicting a taxon that is NOT from South America). This guy's from Asia, Russia to be (barely) more precise.

I'll just leave this skeletal here. You can freely download the full-sized PNG or SVG at Wikimedia Commons if you're interested: https://commons.wikimedia.org/wiki/File:Volgatitan_Skeletal.svg

DISCLAIMER: Yes, I know that the seventh caudal's not figured. No, I haven't seen it (I live in North America). It's just a mutilated clone of caudal six made to look like it actually goes where it is. That's why it's in light gray.

References:

Saturday, December 1, 2018

Carnotaurus Head-On View

Based on Figure 4 of Delcourt (2018).
Dinosaurs generally aren't drawn from this angle. I've been pretty liberal with the amount of flesh on this reconstruction, but it still is surprisingly narrow considering the stout proportions of the skull in lateral view.

Friday, November 23, 2018

A New Kaijiangosaurus

Above is my old Kaijiangosaurus life restoration. I recently did another more detailed restoration to get an image onto Wikipedia's page for this guy:
Restored with the same basic color-scheme, this version has sharper detail, shading, and a more general tetanuran body plan to reflect its uncertain position. This one is tracking down something in a Chinese woodland - perhaps a juvenile sauropod.

On a note related to overhauls, I also redid my Argentinosaurus skeletal. This yields a length of a little more than 32 meters based on Patagotitan (±2 meters, depending on how similar to Futalognkosaurus I restored it). This is rather interesting, since it puts Argentinosaurus as shorter than Supersaurus... perhaps diplodocids still have a say in who's the largest dinosaur after all.

Wednesday, November 21, 2018

Quaternary World - Demented Beasts That Are Oddly Familiar

Ever get fed up with the dinosaur restorations in Jurassic World? If so, then All Yesterdays' section of "All Tomorrows" is probably a source of amusement. But here's a little exhibition designed to mimic the movie. Now all I need to do is get it published as a kid's nonfiction book in the science section! Have fun reading each entry, and see if you can guess which dinosaur/pterosaur/mosasaur each animal represents.

Size: 3 meters
Danger: High
Fun Fact: U-Arctos is a savage unstoppable hunter that can run through an electric fence, no harm done! Its mighty roar is heard as it hunts down its prey, showing no mercy.
Commentary: This is scaled to be slightly longer than the largest Kodiak bear. U-Arctos really should be U. arctos, but no one cares about that, it seems. Hornlets were added over the eyes, and all of the teeth were sharpened.

Size: 2.5 meters
Danger: High
Fun Fact: Felis is a cooperative pack hunter and incredibly smart. Its opposable thumb allows it to turn doorknobs!
Commentary: This is called Felis catus, but scaled to the size of Puma, since Puma concolor is sometimes sunk into Felis. Notice the five nasty switchblade claws on the feet. The presence of canines suggests that there were no lips.
Size: .5 meters
Danger: Medium
Fun Fact: Gallus is a terrestrial speed demon, faster than any other beast! Its sharp, spike-like forelimbs are used to gore prey before it gets ripped apart by its savage downturned beak.
Commentary: Despite having a toothless beak, this was restored with teeth anyways, because why not? Some scientists claim that Gallus had wings and even powered flight, but due to the highly robust build, this seems very unlikely and even outrageous.
Size: 6 meters
Danger: None
Fun Fact: Giraffa was a gentle giant, and will never attack another animal. It is mortally afraid of water and would rather die than wade through it.
Commentary: It turns out that Giraffa are so reluctant to attack that they will allow a large hunter like U-Arctos to slaughter large groups of them before retaliation is even considered. When they do fight, their thin necks, tails, and limbs provide little protection. The skull of Equus was used here because that was initially suggest by scientists.

Size: 2.5 meters
Danger: Low
Fun Fact: With massive spikes on its back and tail, Iguana look fierce but is, in reality, an almost harmless plant eater. They will wave their tails and attempt to lash at assailants, but they'd never do that to a person!
Commentary: This is based on specimens rumored to exceed the commonly stated maximum size of 2 meters. We are proud to say that this is one of the most accurate of all our models.

Size: 4.5 meters
Danger: Low
Fun Fact: This intimidating looking beast is one of the most popular attractions at the park. While its horns are rather alarming in appearance, it is only a plant eater and not very dangerous.
Commentary: Since Ceratotherium fossils are very fragmentary, this has been restored based on other animals. While Diceros seems to be the most similar to this species, healthy speculation was used to restore most of the body, limbs, and tail after Hippopotamus, while the front of the snout was restored after Chelonoidis.

Size: 30 meters
Danger: High
Fun Fact: This sea monster may be the largest animal ever! Its fearsome jaws full of sharp teeth would have ripped apart its primary prey, large sharks.
Commentary: A ridge on the animal's back has been suggested by scientists, so it was added. Modern scientific research suggests that the animal may have had a caudal fin, so it has been given an ultramodern look. The popular length estimate of 8 meters is way too small.

Size: .8 meters
Danger: High
Fun Fact: This big-beaked killer may seem small and shaped like a broken umbrella, but look out! Its powerful feet are deceptively strong, and can pick up the weight of an adult human!
Commentary: The big beak of Fratercula suggests that it swallowed large chunks of flesh, so the keratin sheath was restored with serrations. Claims that the foot of Fratercula were webbed or incapable of grasping are considered to be garbage. If they couldn't grab, how could they perch?

Size: 4 meters
Danger: High
Fun Fact: If Fratercula is scary, then Diomedea is a living nightmare! While it could easily throw around a human, it generally preys on larger animals, so security precautions are considered unnecessary.
Commentary: While some scientists struggle to claim that Diomedea was a piscivore because it was found in marine sediments, the massive size and hooked beak suggest otherwise. This powerful avian must have yanked unsuspecting creatures off the ground and dispatched them in trees before tearing into their carcasses with its savage beak.

Thursday, November 15, 2018

Morrison Sauropod Taxonomic Cataclysm

In Paul's 2016 edition of the Princeton Field Guide to Dinosaurs, an "unnamed genus and species" is listed on page 212. It is known from a downright fantastic amount of material, and is quite a bizarre beast, but no clue about its identity is given (which, unfortunately, seems to be the standard in Paul's Field Guide). I had long wondered what it was. Recently I found out the answer.

It is based on three (!) specimens informally known as "Amphicoelias brontodiplodocus." Informally known because the paper was retracted, and didn't describe them very well. But the reason we're here is to discuss taxonomy, the very problematic form that is used in the paper, to be precise. But while we're on the subject, here's a photograph of the mounted skeletons of "Amphicoelias brotodiplodocus" (or should we name its genus "Superamphibarapatomopus"?):



Image by Jacklee (CC BY-SA 4.0), from Wikimedia Commons
The paper apparently (I get a 404 error when trying to view it) claimed that "Amphicoelias brontodiplodocus" is the most unusual diplodocid ever found, and all other Morrison diplodocids must be reduced to Amphicoelias altus. It was claimed that Diplodocus, Barosaurus, Supersaurus, Apatosaurus, Brontosaurus, Suuwassea, and Tornieria are all one species. While we could go into how morphologically different these species all are, I'd prefer to jump straight into discussing the last two taxa. First off, Tornieria. It's not from the Morrison. It's from... Africa. So, if we can do that, then we need a diplodocid cladogram! Which means: Tschopp (2015)!!!
Cladogram of Diplodocoidea. Modified from Figure 120 in Tschopp et. al. (2015), published under CC BY 4.0.
This means that we can throw in Galeamopus and Kaatedocus (which weren't described at the time), but also Dinheirosaurus from Europe and Leinkupal from the Cretaceous... of South America. And since we've already thrown in Apatosaurus and Brontosaurus in, the unnamed genus gets sucked in as well. Since "Amphicoelias brontodiplodocus" seems to be a diplodocine, it fails to be the extraordinary find that it really is and also gets lumped into Amphicoelias altus. By now all of Diplodocidae = Amphicoelias altus. Dyslocosaurus' dubious status would appear to exclude it. Except...

...Suuwassea. Suuwassea is a dicraeosaurid, not a diplodocid. Which means that unstable taxonomy can't save you this time, Dyslocosaurus. With Suuwassea, we now can lump all of Dicraeosauridae into Amphicoelias altus, including Amargasaurus, Brachytrachelopan, Dicraeosaurus, and Lingwulong. Now Flagellicaudata = Amphicoelias altus. Surely we must be done now?!

Technically, yes, we are, but there still are two trajectories we can go down. The first is assuming that Amphicoelias was used to contain Amphicoelias fragillimus, which just got redescribed as Maraapunisaurus and is now thought to be a rebbachisaurid. If we assume this, then all of Rebbachisauridae is consumed by Amphicoelias altus, and Diplodocimorpha = Amphicoelias altus. Now Haplocanthosaurus is the sole survivor of Diplodocoidea, but if we go to extremes with bad taxonomy, then Haplocanthosaurus is a juvenile diplodocid... and Diplodocoidea = Amphicoelias altus. Even if we ignore Maraapunisaurus this still happens if we sink Haplocanthosaurus.

If we just snag some info from the Wikipedia page on Diplodocoidea, then we can see what we've just done. We've created one species that survived for 81 million years and lived on five different continents. I think it's pretty obvious why the dramatic taxonomic claims in the paper aren't being supported by the scientific community.

Macronarian Cataclysm
We're not done just yet. The paper also apparently hinted that Brachiosaurus and Camarasaurus represent a case of sexual dimorphism. Ignoring obvious errors (3 species of Camarasaurus, one species of Brachiosaurus), what does this mean? Cathetosaurus and Aragosaurus must fall. All brachiosaurids (including Giraffatitan, Europasaurus, Cedarosaurus, Abydosaurus, and Pleurocoelus) must fall.
"Abydotitan"Cedarosaurus. It turns out that this is apparently a Giraffatitan with the head of Abydosaurus.
But if we look carefully, Brachiosauridae falls into the Titanosauriformes clade, but Camarasauridae doesn't. So Euhelopidae can be disregarded as entirely synonymous, in addition to ALL of Titanosauria! That means Alamosaurus, Saltasaurus, Patagotitan, Rapetosaurus, Opisthocoelicaudia, and Malawisaurus are ALL the same animal. And they all seem to fall into... Ornithopsis hulkei! And that's one species spanning from the start of the Upper Jurassic to the very end of the Cretaceous and living on six continents!

So in the end, we get Amphicoelias altus and Ornithopsis hulkei as the only sauropods in the Morrison Formation, in addition to the only certain neosauropods (with Abrosaurus and company being a little unstable). I have no clue how this appears to be reasonable to anybody. Remember, if you're going to propose a radical idea, make sure that you have sufficient evidence to back it up with. This can happen if you don't.


Important Note
Just in case I wasn't clear above, I want to flat-out state that I do not think that this taxonomy makes any sense or should even be seriously considered as a potentially valid hypothesis. I only wrote about it because I noticed that there were some deceptively broad effects from this lumping.

References
Tschopp E, Mateus O, Benson RBJ. (2015) A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda) PeerJ 3:e857 https://doi.org/10.7717/peerj.857

Paul, Gregory S. The Princeton Field Guide to Dinosaurs. 2nd ed. Princeton, NJ: Princeton UP, 2016. ISBN 9780691167664

Also this, this, and this SV-POW post.

Thursday, October 18, 2018

Deinocheirus - What the Heck is it Anyways?



Can Deinocheirus do kung fu? Or is Mongolia to far away?

Deinocheirus is perhaps the embodiment of dinosaurian diversity itself. It shows a variety of different features, including:

  • Hooked thumb claws (present in Spinosauridae)
  • Duckbill (present in some of Hadrosauridae)
  • A heavily enlarged mandible (present in Shantungosaurus)
  • Elongated arms (present in Therizinosauria)
  • A pygostyle (present in Oviraptorosauria and Aves)
  • A dorsal sail/ridge/hump (present in Spinosauridae, some of Carcharodontosauridae, and Ouranosaurus)
  • Shortened legs (present in Majungasaurinae, Metriacanthosauridae, Spinosaurinae, and Therizinosauridae)
  • Strongly arched dorsal series (present in Hadrosauridae)
So, more or less, it's basically a display case of Theropoda's weirdest and a few odd ornithopod features chucked in there. To truly appreciate how strange it is, it might be nice to show it with some other giant Asian theropods.
Same image as before, but Deinocheirus now has a few friends (and enemies... get outta there, Tarbosaurus)!
Let's go through them one-by-one:

Therizinosaurus: This guy rivals Deinocheirus in mass, but was definitely shorter (in length), although apparently taller. With its stubby tail and pot belly, Therizinosaurus was one of the most devoted non-avian herbivorous theropods. Therizinosaurus has immense arms that were about 3.5 meters long (a good meter longer than in Deinocheirus), and they were tipped with sword-like claws. The peculiar thing about these two browsers was that they were contemporaries, both sharing the Nemegt Formation. Perhaps the lack of Asian titanosaurs had something to do with theropods moving in?

Tarbosaurus: If Tyrannosaurus was king, then Tarbosaurus was emperor. The biggest specimens could exceed lengths of 10 meters, and it would have been a formidable beast. This giant theropod was also a resident of the Nemegt Formation, and probably was the main enemy of Deinocheirus (and Therizinosaurus, too). Tarbosaurus is interesting since it has a proportionately bigger head than Tyrannosaurus. It also had a close relative called Zhuchengtyrannus that lived in China. Deinocheirus seems to have been longer and heavier (although I might do a follow-up post on the validity of this statement).

Yangchuanosaurus: For whatever reason, Yangchuanosaurus is often overlooked in arguing over who was the biggest theropod. But this odd theropod was quite large, reaching lengths of 10-11 meters. It was from way back in the Jurassic, and one of the largest theropods of that time, too. It had somewhat shorter legs than other allosaurs, and a rounder head.

Gigantoraptor: This is yet another theropod that grew to giant sizes and assumed an herbivorous lifestyle. At 8 meters long, it was not very big compared to Deinocheirus, but considering that the next largest oviraptorosaur (Anzu) was not even half as long as Gigantoraptor, it was by no means small (unless we start talking about sauropods). The eggs of this giant were each half a meter long and were laid in nests 3 meters across! Unlike Deinocheirus and Therizinosaurus, Gigantoraptor retained long legs.

Ichthyovenator: This enigmatic beast from Laos is a spinosaurid. This critter had a peculiar bifuricated ridge/sail/hump on its back. Like other spinosaurs, Ichthyovenator would have spent its days around or in large bodies of water, hunting a variety of prey items, especially fish. While Deinocheirus was primarily herbivorous, it also ate fish (based on gut contents).

Gallimimus: This slender, cursorial omnivore was a giant among its fellow ornithomimids, at 6 meters long. Gallimimus had very long legs for a theropod, although they actually were on the short side for ornithomimids. It probably was not as fast as Ornithomimus or Struthiomimus, but it still was a dinosaurian speed demon. Ornithomimids are unusual, since they entirely lost their hallux (commonly referred to as a dewclaw). This is one of the many features that allies it with Deinocheirus, and, perhaps surprisingly, is the closest relative of Deinocheirus out of all the theropods in the second image.

Monolophosaurus: The earliest and most basal theropod in our little collection is Monolophosaurus. This five and a half meter long carnivore had an unusual crest on its head, composed of the ridges on its snout. This crest would have been used for display. Monolophosaurus is from the Middle Jurassic, and is one of many odd crested theropods, with the Asian Sinosaurus and the Antarctic Cryolophosaurus also having bony head crests.

Achillobator: This 5 meter animal was a dromaeosaurid, the family of dinosaurs that includes several of our favorite feathered non-avian friends, including Velocriaptor, Deinonychus, and Utahraptor. While not as big as Utahraptor, Achillobator was still huge for a dromaeosaur (although the South American Austroraptor surpassed them both in length). Achillobator seems to be a fairly typical dromaeosaurid, albeit a very large one.

File:Deinocheirus Scale.svg
MPCD-100/127's willing to talk but /18 and /128 are still trying to figure out what that puny biped is. These size comparisons sure can look a little odd sometimes!
So there you have it. There were several large theropods that roamed Asia in the Mesozoic Era, but Deinocheirus actually seems to be the biggest of the bunch. So what does this mean?
  1. Give Deinocheirus the honor of appearing in your mega-theropod size chart (which we're all doomed to make someday) ;)
  2. Even among the giants, theropods still displayed incredible diversity. Wings, tail fans, and herbivory clash with the stereotypical view of claws, teeth, and insatiable carnivory. But that isn't a bad thing. It shows that even among the tyrants and the carchars, it's hard to ignore how mindbogglingly successful dinosaurs were as a whole.
It's a real shame that these wonderful giants are eclipsed by the giant theropods from elsewhere. Rarely do we get to appreciate the levels of diversity achieved by Asian theropods.

References:
  • Paul, Gregory S. The Princeton Field Guide to Dinosaurs. 2nd ed. Princeton, NJ: Princeton UP, 2016. Print. ISBN 9780691167664
  • Since WP:OR doesn't apply to the world of blogging, I've taken the liberty to really closely compare these creatures and draw some parallels.
Skeletals:
Without these guys, I'd be helpless and this post would never exist. Special thanks to the work of all those skeletal drawers out there!
(NOTE:The Ichthyovenator was taken from my old image here. If you're looking for a skeletal of this guy then this one by PaleoGeekSquared is rather good.)

Monday, August 6, 2018

Tylosaurus Strikes Back

Caution: MAY BITE! Image by me, Slate Weasel, published under a CC BY 4.0 license. The main reference for this image was Scott Hartman's skeletal.
Ugh... dinosaurs, pterosaurs, plesiosaurs, ichthyosaurs, pelycosaurs, nothosaurs, protorosaurs, archosaurs... considering that "saur" means "lizard," these names are all rather deceptive and frustrating, especially when people dismiss dinosaurs as "giant lizards." But mosasaurs actually are lizards!

FINALLY!

And it is a mosasaur that currently decorates the banner of Delta, and what better choice is there than Tylosaurus? Tylosaurus is not the largest mosasaur, but is still one heck of a bruiser, and not something that I'd envy meeting while swimming. Sadly enough, marine reptiles aren't featured very prominently in reference books, making digging up information about them rather difficult. However, I've thrown together a small amount of information about this monstrous lizard.

The species that you see above and below is T. pembinensis, currently one of the few mosasaurs that I've found a good skeletal for (maybe I'll find some more someday...). Since T. pembinensis is not as formidable (I mean big) as its relative T. proriger, it appears to be a less popular animal to restore.


That said, it's not like T. pembinensis was small, either. This one is really mad about something related to "his" diver. Image by me, Slate Weasel, published here under CC BY 4.0.
Mosasaurs are often misinterpreted as serpentine swimmers, but that was not the case. A recent study analyzed a specimen of Platecarpus that preserved various soft tissue impressions. The tail had a downward bend, and skin impressions from the upper fluke were preserved. The shape suggests an asymmetrical caudal fin, good for more advanced types of swimming. This tail shape is rather common among marine reptiles, seen also in ichthyosaurs and metriorhynchids (marine crocodiles).

But, since we haven't yet escaped weird taxonomic problems, we're just going to go over the taxonomy of Tylosaurus. T. pembinensis, the species in the two images above, was originally named as a species of Hainosaurus before becoming a species of Tylosaurus. However, Hainosaurus may be Tylosaurus or it may be distinct. It isn't very clear. Even T. proriger failed to escape the chaos. It was given the name Rhinosaurus by Marsh, renamed Rhamphosaurus by Cope (both of which were preoccupied), until it finally received the name of Tylosaurus.

So these are the mosasaurs. Awesome giant marine lizards that get misunderstood and underestimated. Not much progress has been made, even the "frill-backed" version still exists in modern media. Then again, popular media has a knack for getting things wrong. Until the next time, here's one more mosasaur:
Platecarpus, the modern way. By me, Slate Weasel, originally published here under CC BY 4.0.
This is Platecarpus, the one featured by the study I mentioned above. It doesn't look all that lizard-like anymore, to be honest. However, it does look much more streamlined and fast, which is a good thing if you're a marine predator. Oh, and here's one more:
Goronyosaurus, a tough-looking mosasaur. By me, Slate Weasel, oringinally published here under CC BY 4.0.
Okay, I'm really done now.

References