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The digitigrade Taeniolabis meme

February 22, 2017

taeniolabis_nt_smallTaeniolabis taoensis by Nobu Tamura.

Taeniolabis, like most multituberculates, has relatively few artistic depictions. What few depictions there are, however, seem to all be plagued by a common feature: digitigrady.

Above is the relatively recent work of Nobu Tamura, uploaded to Wikimedia, which only the latest in a long line:

taeniolabisArtist uncredited but hosted here.

492758687

89164541Two depictions (alongside other Paleocene mammals) credited as “De Agostini Picture Library”

s-l500Another uncredited picture, hosted here.

taeniolabis_psitaccotheriumv1_by_avancna-d1gjs3aPicture by Stanton F. Fink (also depicting Psittacotherium, meaning that the animal is also undersized)

fossil_mammal_parade_by_paleoaeolos-d64bdloDepiction (alongside many other mammals) by Martin Chavez; also severely undersized.

This leads me to believe that this is yet another paleomeme, one that seems unjustifiable.

There is some evidence that derived multituberculates displayed facultative digitigrady, and indeed I wouldn’t be surprised that some multies were fully digitigrade. However, from what little I can gather from Taeniolabis‘ tarsal anatomy, it seems to have fit the plantigrade model offered above.

The depiction for it’s closest relative, Kimbetopsalis, by  one of its describers Sarah Shelley, seems to agree on a plantigrade model for taeniolabidids:

kimbetopsalis-simmonsae

References

http://www.palaeontologia.pan.pl/PP67/Luo.pdf

Willamson, T.E.,; Brusatte, S.L.,; Secord, R.,; Shelley, S (2015), “A new taeniolabidoid multituberculate (Mammalia) from the middle Puercan of the Nacimiento Formation, New Mexico, and a revision of taeniolabidoid systematics and phylogeny”, Zoological Journal of the Linnean Society, doi:10.1111/zoj.12336

The evolution of herbivory in mammals

February 4, 2017

f3-large

f2-large

So there’s this 2013 study that examines mammalian diversity in relation to the spread of angiosperms, and there are several interesting results. For instance, carnivorous/insectivorous species underwent a decline with the spread of angiosperms, while Argentoconodon is apparently a carnivore while Volaticotherium is an insectivore (both relevant to my flying volaticotheres post). Most interestingly, it paints a rather interesting picture on the development of mammalian herbivory.

As you can see above, through most of the Mesozoic mammals were predominantly animalivorous. By the Early Jurassic there was already a vast diversity of mammalian and quasi-mammalian species; insectivores such as Megazostrodon and Kuehneotherium branched into hard-shelled and soft-prey specialists respectively, while we see the appearance of relatively large sized carnivores like Sinoconodon and the aerial volaticotheres. This trend continues into the Late Jurassic and Early Cretaceous periods, which see a further diversification of mammals into aquatic, fossorial, arboreal and even larger sized carnivorous species. Essentially, we see a guild of insectivores and carnivores in just about any niche available.

However, through most of the Jurassic and Early Cretaceous only one lineage of mammals, the multituberculates, appear to have ventured into herbivorous niches. Even haramiyidans, traditionally considered herbivores or omnivores, range within the insectivore space (though in fairness only one genus is taken into account). And through most of the Mesozoic, multituberculates only do so tentatively, mostly staying within granivore or animalivorous niches. Only in the Late Cretaceous do they venture into fully herbivorous niches, alongside at least two other mammalian clades, the eutherian zhelestids and dryolestoid mesungulatoids (both unaccounted for in the graph but the latter alluded to in the paper).

So, in essence, through most of the age of the dinosaurs mammals were predominantly carnivorous, only occasionally touching granivorous niches until the very end, when fully herbivorous mammals explode in diversity. In spite of their diversity in locomotion methods and size, mammals remained more or less barred from predominantly plant-eating habits until late in the game.

This is in contrast with other groups, such as lepidosaurs and theropods, which did experiment with herbivory early on. Crocodylomorphs appear to follow a similar pattern, with most of the Mesozoic seeing a variety of carnivorous species but only witnessing the rise of herbivorous taxa in the Late Cretaceous; the same might also apply to pterosaurs, if the edentulous tapejarids were in fact significantly herbivorous. The consistent dietary range through time seems to imply that preservation bias is not influencing the results (beyond showing exactly when the “herbivorous turnover” occurred).

This is quite interesting for a variety of reasons. While the paper does warn against equating the evolution of mammalian herbivory with the spread of angiosperms, the fact that the first mammalian herbivores were seed-eaters might imply that mammals were unable to convert into conventional herbivory directly, having to go through a granivore stage first. This clearly applies to multituberculates, though it remains to be seen if it also applies to zhelestids and mesungulatoids.

This might give an insight to how herbivory developed in tetrapods. Tetrapods as a whole are ancestrally animalivorous, but explored herbivorous niches multiple times. It is possible that granivory could have bridged between insectivorous or carnivorous habits and full-fledged herbivory it at least some groups, drawing in through their metabolic rewards but offering a degree of structural complexity that needs to be dealt with. This is particularly interesting in groups such as dinosaurs and anomodonts, in which herbivorous representatives are often beaked or have “buck-teeth” and, like mammals, are endothermic, higher energetic needs that could imply a need for such a transition.

Another important insight is how Mesozoic trophic dynamics changed through time. Mammals were for the longest time barred from an important part of terrestrial ecologies and fulfilled mostly secondary and above consumer roles. This might explain the decline of carnivorous and insectivorous species in the medial Cretaceous, as the higher trophic levels would render them more vulnerable to sudden ecological turnovers. As pointed out in the paper, the more omnivorous therians and meridiolestidans managed to thrive and expanded into the niches left by non-multituberculate mammal groups.

More importantly, this might be part of a much larger turnover. Amidst Jurassic tetrapods only dinosaurs and tritylodontid synapsids appear to have specialised significantly towards herbivory, with a few crocolymorphs and sphenodonts probably veering towards omnivorous habits. Given that the Late Cretaceous sees a much higher diversity of herbivorous tetrapods, including notosuchians, sphenodonts, squamates, turtles and of course mammals, it might suggest that Mesozoic ecosystems couldn’t support many herbivorous guilds we now take for granted, and that floral turnovers such as the spread of angiosperms created new ecological niches that didn’t exist before.

References

http://rspb.royalsocietypublishing.org/content/280/1771/20132110

http://www.nature.com/nature/journal/v512/n7514/full/nature13622.html

https://www.researchgate.net/publication/272791355_A_multivariate_approach_to_infer_locomotor_modes_in_Mesozoic_mammals

Michael J. Benton,Mikhail A. Shishkin,David M. Unwin, The Age of Dinosaurs in Russia and Mongolia

JENNIFER BOTHA-BRINK and KENNETH D. ANGIELCZYK, Do extraordinarily high growth rates in Permo-Triassic dicynodonts (Therapsida, Anomodontia) explain their success before and after the end-Permian extinction?, Version of Record online: 26 JUL 2010 DOI: 10.1111/j.1096-3642.2009.00601.x

 

Patreon

January 26, 2017

Started one:

https://www.patreon.com/Carliro

Largest Mesozoic Mammals

January 26, 2017

Schowalteria clemensi: Known only from one skull, but seems comparable to latter taeniodonts in size, ranging somewhere between 10 to 50 kg. A specialised herbivore.

2. Bubodens magnus: Represented by a single tooth. It is enormous by multituberculate standards, and probably indicative of an animal above 16 kg (it is described as “beaver sized”). Presumably a specialised herbivore.

3. Repenomamus giganticus: Only “giant” Mesozoic mammal known from fairly good material. Measuring about a meter long and weighting at least up to 14 kg. A specialised carnivore.

4. Kollikodon ritchiei: Conflicting sources on this one. It may have been up to a meter long, certainly putting it above R. giganticus (monotremes are proportionally much more robust), but some sources also list it as “platypus size”. A molluscivore or piscivore.

5. Oxlestes grandis: Possibly slightly smaller than R. giganticus. There is some debate about how large its skull was (10 vs 7.5 centimeters), though the former seems to be the most convincing measurements for now. A carnivore.

6. Khuduklestes bohlini: “Subequal” in size to O. grandis. Possibly carnivorous.

7. Mesungulatids: Most sources are rather vague on estimated sizes (in part due to the lack of modern analogues, in part due to how rare postcranial material is), but the larger forms likeColoniatherium seem to be around 6-13 kg. Specialised herbivores.

8. Vintana sertichi: Known from only one skull. Estimated to be around 9 kilos. Specialised herbivore.

9. Altacreodus magnus: Known from various specimens. At around 9 kilos, it is the largest of the Hell Creek mammals. Specialised carnivore.

10. Didelphodon vorax: Known from several remains. The largest of the Hell Creek metatherians at 6-9 kilos. Molluscivore or carnivore.

Did phytosaurs have lips?

January 14, 2017

Mystriosuchus planirostris by @paleoart, the inspiration for this post.

2016 was many things, but one of the best was definitely being the call out year for many archaic paleoartist mistakes. One of these was the absence of lips in many reconstructions, from the skin-wrapped maws of theropod dinosaurs to the bare-toothed saber-toothed cats to the rather ridiculous depictions of entelodonts and other prehistoric mammals as fanged demons. This year saw the publication of various papers showing that teeth do generally in fact need lips to be protected from damage and moistened, meaning that many animals traditionally reconstructed as bared-toothed monsters need a healthy amount of oral tissue.

That said, things aren’t black and white. Crocodilians, after all, still have bare teeth. In one of these papers, Larson et al 2016, it’s been suggested that their aquatic habits compensate for their lack of lips, as humidity certainly isn’t a problem. However, as the Mark Witton link above informs you, many crocodiles go through prolonged periods of life on land without tooth degradation. It also doesn’t cover how terrestrial crocodylomorphs would have coped with the absence of lips, or why many aquatic vertebrates like dolphins (Platanista aside) still kept their lips.

It seems, therefore, that crocodiles are simply off in this regard. Their liplessness actually appears to derived from a highly unusual facial development process, which essentially renders their entire face a single “scale”. This seems to have evolved in order to develop the extensive Integrumentary Sense Organs (ISOs), thinning the facial skin in order to increase sensivity, and it carried over into their terrestrial descendants.

This obviously raises the question of whereas groups similar ecologically and morphologically to aquatic crocodilians underwent a similar process. Where they also lipless, or did they in fact retain their lips, making comparisons to crocodiles all the more questionable?

The Phytosaurs

Phytosaur head diversity by Darren Naish. Taxa included: Smilosuchus gregorii, Pravusuchus hortus, Mystriosuchus westphali, Paleorhinus bransoni and Pseudopalatus pristinus.

Phytosaurs were, in some respects, the “original crocodiles”, having evolved and prospered long before crocodylomorphs ever touched the water. Although they weren’t particularly closely related (birds are closer to crocodiles than phytosaurs are), these archosauriform reptiles did hit most of the same notes as crocodiles: barrel-shaped bodies, extensive osteoderm armours (in some cases even better protected, due to the bell-shaped cap on the throat and various scutes on the forelimbs and belly), generally short limbs and large, paddle-like tails.

While some phytosaurs explored odd ecological niches – Nicrosaurus and similar taxa are adapted to a primarily terrestrial lifestyle,  while Mystriosuchus was inversely so specialised to life in the water that it was practically the Triassic Metriorhynchus -, a generally semi-aquatic lifestyle for most phytosaurs can be inferred due to due sheer prevalence in freshwater and shallow marine deposits, limb proportions and shape, laterally flattened and powerful tails and retracted nostrils (though keep reading).

Various tracts attributed to these animals similarly imply a close functional match between phytosaurs and crocodiles. Various swimming tracts have been attributed to phytosaurs, while the Apatopus footprints show an interesting insight on these animals’ terrestrial locomotion capacities, being capable of an erect gait like archosaurs and mammals, including modern crocodiles and alligators. Paleopathology studies indicate similar behaviours such as interspecific biting (hence the need for strong armour), and perhaps more damningly endocast studies show that the general phytosaur brain shape was rather similar to that of modern crocodilians (albeit with a few differences, like the size of the brain and the presence of multiple sinuses; see below).

For all intents and purposes, phytosaurs were functionally crocodilian, offering one of the most extreme cases of convergent evolution ever recorded. But no matter how close, phytosaurs were still off the mark in various ways.

Phytosaur facial anatomy and morphology

Pseudopalatus buceros skulls, exemplifying the general morphology of phytosaur skulls as well as interspecific variation. Notice massive premaxila.

The most classical thing you’ve ever heard about phytosaurs was how they differ from crocodiles in having the nostrils be close to the eyes/on top of the head rather than at the tip of the snout. This is true; as you can see, the nostrils are located in front or above the eyes in a “volcano-like” elevation; combined with the nostril-less and often conical snouts, this gives them a distinctive dolphin-like profile.

Like in cetaceans, this nostril placement would come in handy on a mostly aquatic lifestyle, avoiding drag and allowing the animal to surface only a small part of the head and remain concealed underwater. However, unlike cetaceans – and marine reptiles such as plesiosaurs -, this nostril position is not derived from nasal retraction. In fact, phytosaur nostrils are sometimes noted as being rather protracted, sometimes as a result of the general elevation of the nasal region.

Instead, what happened is that phytosaurs elongated the premaxila at the expense of the other skull bones. Unlike crocodiles – and whales and plesiosaurs and many other aquatic tetrapods -, half or more of the phytosaur upper jaw is composed of a single bone, normally a vestige at the end of the jaw in most amniotes, that expanded radically. This hints at a pretty rapid elongation of the snout, explaining maybe why long-snouted phytosaurs appear “out of nowhere” in the fossil reccord.

Predictably, this could also hint at rather atypical development, which is etremely important in dictating the presence or absence of lips.

Another frequently cited difference is the presence of antorbital fenestrae. These are the famous “holes” in front of the eyes present in most dinosaurs and other archosauriform reptiles. Crocodiles have lost them, but they are present in phytosaurs, though they can be reduced in some species. Perhaps associated with this, phytosaurs also have extensive antorbital sinuses, while crocodilians lack them altogether. Phytosaurs also have an extensive premaxillary sinus, though as crocodilians have most of their snout taken by the nasal airways this may not make a lot of difference.

With a few exceptions, most aquatic crocodilians have conical teeth; they compensate for the lack of meat-cutting speciations with the infamous “death-rolls”. Phytosaurs, by contrast, generally have serrated teeth, and combined with the presence of crests on many specimens it seems unlikely that these animals engaged in “death-rolls”, instead opting for more typical meat-eating behaviours. To date longirostrine phytosaurs are the only “gharial-like” vertebrates with serrated teeth, and it might explain why they were frequently associated with the carcasses of terrestrial vertebrates like rhynchocephalians and dinosaurs.

Unlike the teeth of crocodiles, phytosaur teeth seem to be rarely interlocked. Even without lips, it seems likely that the upper jaw teeth covered the lower jaw ones.

What about the lips?

Leptosuchus skull, illustrating the basic points for and against phytosaur lips. For are in red: anteorbital fenestra and serrated teeth. Against are in green: long prexmaxila, POSSIBLE ISOs, front teeth POSSIBLY too large to fit within lips. The latter two are of course ambiguous.

With the above in mind, the absence for or against phytosaurian lips is…mixed.

The rapid premaxilary development in phytosaurs is the key to understanding how the jaw integument of these animals worked. It is possible that the premaxila’s growth prevented the formation of conventional lips, either due to physical and metabolic constraints or because the same genes triggering it could have prevented the development of lips. Perhaps the same pressures causing the crocodilian “single scale” would have been forced on phytosaurs by this developmental quirk.

On the other hand, other parts of the phytosaur skull anatomy seem to suggest the presence of lips:

  • The aforementioned antorbital fenestrae suggests that the phytosaur skull was less “skin-tight” than that of crocodilians. In modern birds, the only living reptiles with antorbital fenestrae, that area of the skull is covered by various soft tissues, and indeed areas of the avian beak devoid of a rhamphotheca tend to be covered by fleshy lips.
  • Serrated teeth tend to be more vulnerable than conical teeth to degradation, so most predatory animals that possess them have them covered by lips. The only crocodilians with clearly serrated teeth are terrestrial species and the fairly basal thalattosuchians, which are still on the limbo on whereas they had lips or not.

It is possible that phytosaurs found themselves in an unique integumental arrangement. Perhaps they did become lipless, with a “single scale” covering the jaws, while the rest of the head had a more normal integument.

A deciding factor in this argument would be the discovery of ISOs on phytosaur jaws. However, structures associated with these organs, such as pits, are rarely discussed outside of the context of pathology when it comes to these animals. There is plenty of literature on pits and holes in phytosaur skulls being caused by fights and bites, but few on any possible natural ones.

Conclusion

Modern Ganges River Dolphin. Although it has exposed teeth, it’s also not the norm among cetaceans.

Just because something resembles another doesn’t mean that there is an exact equivalency. Case in point: no matter how close phytosaurs got to crocodilians, they still differed in many aspects, and could not be mistaken for them in life.

It’s clear that skin-wrapping is a tremendous lack of apreciation for the organic nature of extinct animals. The lack of lips in crocodilians has been taken far too long to be the “norm”; but, as it turns out, it is an anomaly among the usual amniote tendencies.

We may never know for sure whereas phytosaurs had lips or not. Hell, it’s even possible that some had while others went full Platanista. However, far too often are they taken to be crocodile-like for granted, without other possibilities, equally as valid as they are, taking into consideration.

Hopefully, further research will grant us insights on how these already spectacular animals looked in life.

References:

Reisz, R. R. & Larson, D. (2016) Dental anatomy and skull length to tooth size rations support the hypothesis that theropod dinosaurs had lips. 2016 Canadian Society of Vertebrate Paleontology Conference Abstracts, 64-65.

Grigg, G., & Kirshner, D. (2015). Biology and evolution of crocodylians. Csiro Publishing.

Soares, D. (2002). Neurology: an ancient sensory organ in crocodilians. Nature, 417(6886), 241-242.

Stocker, M. R. & Butler, R. J. 2013. Phytosauria. Geological Society, London, Special Publications 379, 91-117.

Kimmig, J. 2013. Possible secondarily terrestrial lifestyle in the European phytosaur Nicrosaurus kapfii (Late Triassic, Norian): a preliminary study. Bulletin of the New Mexico Museum of Natural History and Science 61, 306-312.

Gozzi, E. & Renesto, S.A. 2003. Complete specimen of Mystriosuchus (Reptilia, Phytosauria) from the Norian (Late Triassic) of Lombardy (Northern Italy). Rivista Italiana Di Paleontologia e Stratigrafia 109(3): 475-498.

Michelle R. Stoker; Sterling J. Nesbitt; Li-Jun Zhao; Xiao-Chun Wu; Chun Li (2016). “Mosaic evolution in Phytosauria: the origin of long-snouted morphologies based on a complete skeleton of a phytosaur from the Middle Triassic of China”. Society of Vertebrate Paleontology 76th Annual Meeting Program & Abstracts: 232.

Merry Churisutumasu: Redux Evolution

December 25, 2016

Chibi Ursa and Helios were very sad. Everyone they knew was dead, and it was Christmas Eve. They sat alone in a café in Siberia. Suddenly a guy with a parka yelling homophobic slurrs came out of the bushes and shot Helios!

“No!” cried Chibi Ursa bitterly, now she was truly alone in the darkness of the mind’s cosmos.

“Hahahahahahahaha how your pussy fucks yourself!” mocked Donald Trump evilly, he was nearby drinking beer.

Chibi Ursa then took out a horn clipper and threw it at his crotch, utterly annihilating it in a shredded blending of gore as his genitals turned into red mist, then red snow, then a red glacier. Lots of bats and rats entered through his exposed urethra, stretching it in a bulbous way kind of like opossum joeys in the pouch, except there was BLOOD and PUS, red and green like the colours of SANTA, accept more dirty.

Well anyways a dimensional portal appeared, and out of it came………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..USAGI!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

“WTF?1” said Chibi Ursa wonderingly.

“Chibi Ursa, you must save this timeline!” said Serena, she had an ipatch like Danger Mouse, “Santa plans to return with an army of the damned! I managed to defeat him in this universe, but for that reason there are now TWO Santas in HELL and they fused together!”

“OFMG does that mean everyone else is alive in your world?” asked Chibi Ursa happily.

“No, the Guardians killed them all before they joined Justice League Dark” said Usag sandly, “There is no time! We must reach the obsidian temple before-”

Suddenly, a spring of lava springed out of the ground, spearing Serena from her pussy to her brains! Her organs were blackened by the heat and expelled noxious gases, burning her skin to a dark crisp and inflating her fingertips like fleshy balloons (kind of like those bubbles you get when you touch a lamp, only more plastic) and exploded her phalanges in a shower of bloody vapour, her nails being projected thousands of miles into the earth’s crust, leaving tunnels that were quickly filled by molten rock.

From these tunnels came an evil red smoke, followed by hands of rock. Chibi Ursa couldn’t believe it……………………………………………………………………………..LAVA ZOMBIES!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! They ated Serena’s corpse, and then began to sprout tendrils, that began to sew them together, until they formed……………………………………………………………………………………………………………………………………………………………………………………SANT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

“Ho ho ho merry FUCKING cHRISTMAS!” said Santa, punching Chibi Ursa in the face, obliterating her jaw into a billion butterfly-like shards and sending her flying miles away, destroying entire mountain ranges.

It seemed like defeat. Lava zombies, demons, gorgons and Rockettes came out of the earth and ate people, raped children with kitchen utensils and bribed politicians to increase global warming. All snow melted, and Christmas seemed ruined. Santa walked all over Asia before he sat in his lava throne in Japan, causing earthquakes all over the Earth. Chibi Ursa kept flying all over the planet, obliterating everything in her path, serving the very evil she sought to destroy. To make things bad, her jaw got infected with necrosis, and her tongue became a white, shriveled sack of pus.

But she remembered. She remembered her friends, their smiles, the Christmas spent together. She remembered the joy, the unity, the communism. She remembered the snowy winters, the snowbite and the snowforst, and how it dulls the senses and the ego.

And she did not give up.

“By the power of Christmas, I will defeat you Santa!” she declared.

And a miracle happened. Her jaw, she got a new jaw………………………………………………………………………………………………………………………………………MADE OF ICE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

“Sweet, now I can eat any mexican food I want!” she chirped happily, clapping her hands like a baby of righteousness.

She used her new found cryokinesis to freeze time and space, so she slowed down and repaired all the damage she had caused. All the undead looked at her, but she blew an icy kiss and they all froze to DEATH, their lava turned into blue ICE.

“What is the meaning of this!?” yelled Santa, who rose from his evil throne and caused a lava torrent to project all the way to the Moon with every step he took.

“Santa, your evil christian ways will end!” said Chibi Ursa, “Surrender or return to the HELL from where you came!”

Satan got MAD, and he casted a spell, melting the earth and turning it into reindeer of lava and molten metal. But all Chibi Ursa had to do was to send a blizzard, and they all died.

“GRRRR, you shall PAY!” growled Santa, and he took off his pants and masturbated!

He ejaculated pure black ash-like semen into the earth, and it began to shake. Suddenly, a Rudolph made of lava came! Chibi Ursa summoned another blizzard, but Rudolph had a nose made of the Earth’s core!

“Ho ho ho if you attack then the entire planet will die!” cackled Santa evilly as he ate his cum.

Chibi Ursa thought a bit. Then she had an idea!

“Rudolph, if all other reindeer are made of lava, doesn’t that mean your nose isn’t special anymore?” asked Chibi Ursa piercingly?

Rudolph’s eyes widened. All the suffering, all the bullying, was meaningless now. He had an identity crisis! He stared blankly, lost in his own thoughts.

This was all it took for Chibi Ursa to jump on his head and take off his molten gold obsidian antlers. She could touch them became she froze her hands, so there was a heat imbalance and lightning flew everywhere. She focused all the lightning on the antlers, then jumped out of Rudolph into Santa!

“Santa, your ass belongs to HITLER!”

“No!” cried Sainta, but it was too late!

Then she stabbed him in the head, ripping his skull apart and frying his brains with lightning, making him clinically retarded and shit his internal organs. He died, and his corpse became Usagi’s.

Chibi Ursa buried her mother in the molten earth, which then cooled down and became ice. It quickly covered the entire planet, quenching the fires and bringing a white Christmas even to the tropics.

She returned the antlers to Rudolph, and the two sat together on a glacier, enjoying each other’s company. They were the only family both of them had left.

Amen.

Visual references for Dryolestoidea

December 22, 2016

Researching extinct mammals can be extremely taxing, especially when most you have are teeth and jaws and when what aren’t teeth and jaws is often only ever available in pay-walled, often esoteric texts.

Ditto for dryolestoids, one of the most fascinating of non-therian mammal groups; you wouldn’t guess that a clade spanning at least 60 species across all continents from the Jurassic to the Miocene, ranging from insectivores to hyrax-like herbivores to diggers to weird tusked pseudo-pigs, would have little more than a few pics that aren’t teeth in its name. And sometimes even those are hard to get by!

So here’s some aid:

A possible template?

image

So before we get to the many fossil dryolestoids, we should get to what might be a living representative of this clade(!). According to one 2014, the living “marsupial” moles might actually be dryolestoids rather than marsupials.

Thus, it’s a tempting idea to keep Notoryctes in mind. Even if it is a marsupial after all, it is nonetheless very similar to at least one dryolestoid, Necrolestes, and you can always spice up your art with a few details based on this wondrous creature.

However, it is nonetheless a very specialized animal. Comparing the “marsupial mole” to, say, Henkelotherium is like comparing a mole to a cat: it’s not going to work. So keep that in mind.

Necrolestes

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image

Necrolestes patagoensis skull and skeleton. Later image by Gabriel Lio.

Necrolestes is by far the best illustrated of all dryolestoids, thanks to it basically being a victorian paleontological meme. It is very similar to the still living “marsupial mole” – and almost certainly it’s closest relative if it is a dryolestoid – differing mostly in details of the head, with a strange up-turned snout and prominent fangs.

Like the “marsupial mole” it is too specialised to be a model for every dryolestoid however. For instance, although the Cretaceous south american Leonardus is closely related to it…

Cronopio

image
image

…so is Cronopio, an entirely different animal altogether.

Armchair anatomists might find the above skull to resemble that of a pig, and that’s basically what Cronopio was: a tusked, long snouted omnivore, even edging on the size of small suines.

Many an online article compare this thing to Scrat, the saber-toothed squirrel from the Ice Age movies. However, from what we know it seemed to have been a terrestrial forager, and probably not particularly squirrel-like.

It is nonetheless not a very mole-like animal, unlike either Necrolestes or the “marsupial moles”.

Henkelotherium

What is squirrel like, however, is the Jurassic aged Henkelotherium, from my home country of Portugal.

This animal is completely unlike the previous ones: rather than being robust, it is very gracile, and rather than digging on the ground it lived on the tree canopy. In the Jurassic it seems virtually every mammal group had an arboreal representative (be it the docodont Agiloconodon, volaticotheres, haramiyidans or early therians, among others), and as it turns out dryolestoids were no exception.

Crusafontia

Another dryolestoid frequently depicted as arboreal and squirrel-like is Crusafontia; however, this is a holdover from when its remains were considered to belong to an early primate, and it’s probably impossible to confirm given that we only know it from a few jaws and teeth.

However, being a diverse group as it was, Dryolestoidea probably had several more arboreal species, and it’s certainly possible that many taxa we only know from teeth were in fact arboreal.

Dryolestes

Very few discussions are complete without the eponymous genera. Compared to other dryolestoids, Dryolestes itself is laughably underrepresented in so much as diagrams, but there a bit we can glean from the jaws we have.

For starters, by Jurassic mammal standards it was fairly large, being roughly the size of a hedgehog. It probably lived like one as well, judging its fairly generalized teeth yet robust jaws.

Keep in mind that we know some Mesozoic mammals had spines (i.e. Spinolestes) or otherwise crazy hair (Volaticotherium, with its long tail bristles), so it’s very likely dryolestoids were doing similar things. This is an aspect of mammalian paleoart that seriously needs exploring.

Mesungulatoids

(First two pictures belong to Peligrotherium. Last is a molar of Mesungulatum)

The most spectacular of all dryolestoids were probably the mesungulatoids, a herbivorous lineage that diversified during the Late Cretaceous of South America, and endured for a few million years into the Paleocene, achieving megafaunal sizes in the case of Peligrotherium.

Most frustratingly, they’re also the hardest to find good pictures of, as the most complete skull yet is available only on a paywalled paper.

In general, we know that these animals had blunt snouts, as the thick and up-turned jaws above can clue you in, packed with batteries of strange molars. In this regard maybe the also blunt skull of the “marsupial moles” might serve as a good reference.

And more

Austrotriconodon molar

Hopefully the above might have helped you get a basic picture of dryolestoid diversity and apparence.

Sources:

Kielan-Jaworowska, Zofia; Cifelli, Richard L; Luo, Zhe-Xi (2004). Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure. New York: Columbia University Press. ISBN 978-0-231-11918-4.

Agnolin, F.; Chimanto, N. (2014-12-22). Morphological evidence supports Dryolestoid affinities for the living Australian marsupial mole Notoryctes”. PeerJ Preprints. 2: e755v1. doi:10.7287/peerj.preprints.755v1.

Dental and Craniomandibular Anatomy of Peligrotherium Tropicalis: The Evolutionary Radiation of South American Dryolestoid Mammals, ProQuest, 2008

Guillermo W. Rougier, Sebastián Apesteguía and Leandro C. Gaetano (2011). Highly specialized mammalian skulls from the Late Cretaceous of South America”. Nature. 479: 98–102. doi:10.1038/nature10591.  Supplementary information

Gaetano, C. A. Marsicano, and G. W. Roughier. 2013. A revision of the putative Late Cretaceous triconodonts from South America. Cretaceous Research 46:90-100