What did a dinoceratan do?

Ooh... Turnbull reference is online:
http://www.archive.org/details/mammalianfaunaso47turn

What on earth did Gobiatherium do with those enormous nostrils?:O

Why do these have some many ribs? It seems like that it had too many compared to length to the Smithsonian mounts. How many ribs did it actually confirmed have?

The Thunder-Bunny Theory: Dinoceratans came from Asia to America during Late Paleocene, and they've not been found in Europe. An Asian center for this group is coherent with a relationship to Anagalids and Glires. Arctostylopids were another group of Asian "protungulates" related to Glires.

Is...is that a nostril? o.O Jeeze, Gobiatherium's weird...

I linked to this, and my Facebook friends are now following up with questions on whether the "giant horned bunnies" have any connection to jackelopes. I'm trying to keep a straight face as I invoke Jungian archetypes in my response.

I know it has been discussed here before but does the amphibious lifestyle make any more sense for dinoceratans than say astrapotheres?

Okay, Gobiatherium is driving me nuts. Not because I can't figure out what the big nostril was for (although I can't), but because I _know_ I have seen a nostril like that on the skull of something else, but I can't remember what or when. Help me!

Matt: My daughter says "crocodile", and demands I pass it on.

MattL Does it remind you of Diprotodon? That was my first reaction (aside from "eeek!").

Chris Taylor asked a while back whether the Paleogene 'archaic' mammals were actually placental.

http://catalogue-of-organisms.blogspot.com/2008/09/life-in-palaeocene-w…

Any thoughts?

Dinoceratans, because Dinosaurs were just a phase, right?

Matt: though not a mammal and so not too closely like the skull Gobiatherium does kind of remind me a bit of Altirhinus the asian iguanodontid.

They lived in North America 50-45-mya. Their brains were small, were Rhino like Bizarre head structure bearing horns and rather large canines. Vegetarians.

Thanks to all who have tried to help me recall the thing I can't recall. All your suggestions are apt, but none are what I am thinking of. Whatever it was didn't have a nose that was merely reminiscent of Gobiatherium, it had that exact profile, with the nearly circular naris and the big internarial bar rising up like a hemisphere from the otherwise flat rostrum.

This is like when you're trying to remember someone's name and it doesn't come to you for at least a couple of days. It's maddening. Please keep the guesses coming, I really appreciate the help.

Two long questions: (Obscenely absurd but sincerely asked) 1) What are the chances that the upper full skeleton is a direct ancestor to the more recently extinct saber-toothed kangaroo? 2) Did pig ancestors previously spend 1/2days as "shallow hippos", munching marsh mallows/sedges/soft clams/crabs while part-submerged in warm swamps & beaver ponds, often immobile, just beyond the (northerly?) limits of big crocs? That would explain warthogs, peccaries, babirusas in tropics being mud friendly but not aquatic, and African rock river hogs tipping fast-river pebbles seeking crustaceans but avoiding slow water, and pigs having a blanket of skin fat yet being poor swimmers/divers and no flipper-like feet. Their fat and lung air would have prevented their sharp feet from sinking in wet mud while root grubbing underwater, and they could simply roll laterally like a steam roller if their feet did get stuck. Their habit of 'poor' hygiene is similar to hippo fanning, as a way to keep cool during drought. But while hippos have 'blood' sweating against sunburn, pigs don't, so maybe they were in water at dawn & dusk using their disc nose to feel around the muddy bottom like the star-faced mole does with its tentacled disk, spending the day foraging the forest floor and night in burrows or old beaver lodges (don't warthogs use aardvark dens?).

Matt Wedel wrote:
"Okay, Gobiatherium is driving me nuts. Not because I can't figure out what the big nostril was for (although I can't), but because I _know_ I have seen a nostril like that on the skull of something else, but I can't remember what or when. Help me!"

> eeer... Do we have to suppose a convergent lifestye? Sexual dimorphism? Similar habitat? Is it useful to compare an ancient mammal with an ornithopod? Let's see:

Muttaburrasaurus langdoni
Image:
http://en.wikipedia.org/wiki/File:Muttaburrasaurus_skull_aus.jpg

Altirhinus kurzanovii
Norman, D.B. 1998. On Asian ornithopods (Dinosauria, Ornithischia). 3. A new species of iguanodontid dinosaur. Zoological Journal of the Linnean Society. 122: 291-348
Image:
http://www.oucom.ohiou.edu/dbms-witmer/images/Altirhinus02.JPG

Darren:

I'm shocked to find that Gobiatherium seems to have no internet presence at all

It is hardly any more prevalent in the printed literature. There is, however, a reconstruction of Gobiatherium in Björn Kurténâs 1971 book Age of Mammals.

Even though I've heard Turnbull's aquatic theory advanced in books for dinoceratans, I've yet to see any real evidence put forth to justify the idea, or any persuasive evidence for them being rabbit relatives (though the idea's an intriguing one, to be sure.) Most depictions of the dinoceratans, at least the large ones, depict them as the ecological equivalent of rhinos, a view that I must admit I find much more attractive. These animals are interesting to me because they possess a combination of features not found in the modern world: they're flamboyant, bizarre, "prehistoric" if you will.

Bibliographical trivia:
Lucas & Schoch in the 1998 Janis et al. volume is not the original source of the "giant horned bunnies" formulation of the hypothesis that Dinoceratans had Anagalidan affinities: it's quoted there.
I'm pretty sure it occurs in Lucas (& co-author I can't remember), "(list of taxa including Uintatheres and some South American endemics) are not ungulates,"(*) in
F.J. Szalay, M.J. Novacek, & M.C. McKenna, eds., "Mammal Phylogeny, vol. 2" (Springer-Verlag, 1993),
and may-- I can't remember-- be quoted there from an even earlier source.
--
(*) Article arguing that the listed taxa are not part of a monophyletic "Ungulata" based on extant Artiodactyls, Perissodactyls and Paenungulates: 1993 was before the molecule-based idea that Paenungulates are Afrotheria, far from the "Laurasiatheria" containing the other two. And I think Artiodactyls and Perissodactyls are no longer assumed to be as closely related as they once were. So a modern statement of the claim in the title of Lucas & X would have to be:
"There is no such thing as Ungulata, and, even if there were Uintatheres wouldn't belong to it."

Quoth Matt:

Okay, Gobiatherium is driving me nuts. Not because I can't figure out what the big nostril was for (although I can't), but because I _know_ I have seen a nostril like that on the skull of something else, but I can't remember what or when. Help me!

Hmmm...

Muttaburrasaurus is what leaped to mind for me. In general outline, it also reminds me of an ornithocheirid skull, though obviously in that case there's no nostril occupying the lump at the anterior end.

Also just wanted to point out that if dinoceratans are somehow connected with Glires, then they are more closely related to you and me than to rhinos or hippos.

A very odd thought.

What are the chances that the upper full skeleton is a direct ancestor to the more recently extinct saber-toothed kangaroo?

The saber-toothed what?

If, by any chance, you mean Thylacosmilus, which had in common with the kangaroos that it was a notometatherian (and nothing else), then no: all of the animals depicted here are very clearly eutherians (just like the placentals are), not metatherians.

Did pig ancestors previously spend 1/2days as "shallow hippos", munching marsh mallows/sedges/soft clams/crabs while part-submerged in warm swamps & beaver ponds, often immobile, just beyond the (northerly?) limits of big crocs?

Short answer: no.

Also, what's so strange about subcutaneous fat? Everyone has that, cows included.

And the star-nosed mole uses its famous nose in dry burrows, not only in water.

Allen Hazen: I remember that paper too. The authors suggested that dinoceratans, pyrotheres and xenungulates form a clade Uintatheriamorpha that is related to anagalids while pantodonts and tillodonts are ... something else, I don't remember what.
Lucas already suggested this in a 1986 paper on pyrotheres:
http://www.geologia.ucr.ac.cr/revista/05/05-LUCAS.pdf
But then the pyrothere ear region is similar to that of notoungulates (Lucas mentions however that some of these characters are also present in dinoceratans).
In "The beginnings of the age of mammals" by Rose (partly online at Google Books) it is said that the xenungulate Etayoa is much less similar in dental morphology to dinoceratans and (derived) pyrotheres than Carodnia is, but more similar to basal astrapotheres. Also, the only evidence for a relationship of dinoceratans to anagalids seems to be their teeth, the rest of the skeleton is very different.

A relationship between uinthatheres and some South American ungulates would be biogeographically analogous to pantodonts and Bolivian Alcidedorbignya. A linkage between South America and Asia without recognizable North American link would point to some complex Gondwanan route, maybe Antarctica-Kerguelen-Greater India, with Southern Asian and S.American offshoots.

I don't know if it would be a problem: If dinoceratans had great canines, it would make impossible a relationship to Glires ancestors?

If dinoceratans had great canines, it would make impossible a relationship to Glires ancestors?

No: starting from a common ancestor, Dinocerata would have enlarged the canines, while Glires would have lost them.

@ 22 - DM, no not Thylacosmilus. "Through the fossil record we have had wombats the size of elephants and sabre tooth kangaroos but they became extinct many thousands of years ago", from an Australian marsupial paleontology major. http://answers.yahoo.com/question/index?qid=20080406175021AAB75AX

Henk Godthelp, a UNSW vertebrate paleontologist, says the new kangaroo discoveries include a saber-toothed species that may have used its large teeth for grooming or to attract mates. "[The teeth] don't really look [like] anything used to rip intestines out of unsuspecting prey," he said. Nat'l Geog. 2006/07
"clearly Eutherian" Ok. William Montagna on mammal skin found unique similarities in amount of subcutaneous fat elastin in pig skin and humans, (I'd suspect also in hippos and manatees). Human infants have white and brown SC fat and can't shiver or group nurse, piglets have no brown fat (since 20ma, UCP1 gene) and shudder to get warm and group nurse in dens. I think the star nosed moles favors wetlands, in comparison to most moles, but agree they must have dry burrows.

With so much paleontological findings and phylogenetic new assumptions and re-assumptions, Placental phylogeny became such a mess, with many opposite theories being stated.

Anagalids would fit in Euarchontoglires next to Euarchontan, to Glires, or basal to both ones? Basal Glires were obviously Asian, basal Euarchontan could be Asian, since Dermopterans and tree-shrews are South Asian-endemics, Primates' and Plesiadapiformes' has a dubious origin, Purgatorius from Cretaceous-Paleocene N.America, but without clear ancestors.

Well, except that Purgatorius is, I think, no longer believed to be euarchontan. Instead, it's a stem-eutherian. Which actually makes your scenario easier to be true, since there is no need to explain an American relative in the Late Cretaceous/earliest Paleocene.

Wible et al. (2007) did place Purgatorius as a sten eutherian (along with Protungulatum and Oxyprimus), but forcing it into its traditional position was not significantly worse.

Excluding Purgatorius, Plesiadapiformes appears in N.America in Lower Paleocene (only Pandemonium, Puercan and a "explosion" in Torrejonian with lots of genera and families, together with the dubious Mixodectidae and Plagiomenidae). Asian Glires reached American only during Upper Paleocene. I think this "suddenly" rise of Plesiadapiformes in America could came from Eastern North American or European ancestors. Mammalian fauna in Europe is poorly known before Upper Paleocene, with only Fontllonga and Hainin sites in Lower Paleocene(until now only few species recovered)

Gobiatherium reminds me of the pleistocene marsupial zygomaturus, which probably had a lifestyle similar as the still living Pygmy Hippo.

I don't know how Gobiatherium lived but could it not live in a semi-desert like environment and used it's 'nose' in somewhat similar fashion as a saiga antilope ?

Wible et al. (2007) did place Purgatorius as a sten eutherian (along with Protungulatum and Oxyprimus), but forcing it into its traditional position was not significantly worse.

The one problem I have with that analysis is that all characters were unordered. This can change the topology, and it can increase (!) the stability of the tree by masking character conflict.

Henk Godthelp, a UNSW vertebrate paleontologist, says the new kangaroo discoveries include a saber-toothed species that may have used its large teeth for grooming or to attract mates.

Ah. Well, then it's a kangaroo -- and dinoceratans are not kangaroos.

DDeden:

pigs having a blanket of skin fat yet being poor swimmers/divers

Everything's relative, of course, but I wouldn't call pigs particularly poor swimmers. In fact, for being mainly terrestrial animals I'd say they swim pretty well (especially Sus scrofa).

Their habit of 'poor' hygiene is similar to hippo fanning, as a way to keep cool during drought.

Are there any studies suggesting that hippo 'fanning' actually has any thermoregulatory function? I thought they're only spreading their shit around (to put it bluntly).

Henk Godthelp, a UNSW vertebrate paleontologist, says the new kangaroo discoveries include a saber-toothed species that may have used its large teeth for grooming or to attract mates.

I don't think it's technically correct to call it "saber-toothed". Ekaltadeta - which is the taxon Godthelp was presumably referring to - has elongated lower incisors, yes (picture here). But "saber-toothed" is a term that has traditionally been reserved for mammals with elongated canine teeth. And Ekaltadeta, like all other kangaroos and indeed all Diprotodontia AFAIK, lacks canine teeth altogether. Calling it saber-toothed is, frankly, misleading.

@ 35 - Well pigs can swim better than many animals. I think they went through a tropical almost-"swamp seal"-like stage or so, but have since returned to a more terrestrial habitat, as elephants and rhinos, yet retaining the white fat blanket due to having lost the brown fat gene. Their diving reflex is similar to dogs, weaker than human freedivers, beavers and muskrats, and far weaker than seals.

Hippo fanning spreads muck around, elephant trunk spraying spreads murky water around, pigs roll around in muck, I think this usually happens during mid-day heat, its most helpful when water levels are low in the dry season, cooling sun-block being harder to come by then.

I agree, 'saber tooth' isn't the best name, if its referring to Ekaltadeta. I thought they meant another kangaroo with upper sabers, but apparently not. Still a strange beast.

I think they went through a tropical almost-"swamp seal"-like stage or so, but have since returned to a more terrestrial habitat, as elephants and rhinos

Elephants perhaps, but not rhinos, and not pigs either. You see, you have a fossil record to argue with.

Hippo fanning spreads muck around

No, it spreads shit around (very far -- zoo visitors, beware!) and has pretty clear territorial functions. Hippo tails are way too short to spread anything over enough of the body for a thermoregulatory function.

I think this usually happens during mid-day heat

Don't come back before you've found out whether this is actually the case. If you build an argument on an untested assumption, the entire argument is a castle in the air as far as science is concerned.

@ 37 - DM, please see comments:
http://scienceblogs.com/tetrapodzoology/2009/07/inside_natures_giants_p…
Elephants, rhinos (since the tapir/rhino LCA) and pigs (since the whale & hippos split away) have all become more terrestrial AFAICT, based on digit reduction etc. http://www.csus.edu/indiv/L/lancasterw/bio168/LABS%20BIO168-03/LAB%2018… Do you have evidence indicating that they have all become more aquatic? Hippo tails are obviously long enough to spread mucky manure around, probably a dual role mechanism, communal cooling & territoreal boundaring. I have no idea of their defecation routine, but its probably after the sun has risen and before sunset.
"castle in the air" = the ISS? Nice place to visit, but I wouldn't want to live there.

@ 35 - actually, Henk was referring to 'fangaroo', a balbarine kangaroo from the Oligo-Miocene of Riversleigh formally described as Balbaroo fangaroo by Bernie Cooke in 2000. This taxon has (for a kangaroo at least) very tall upper canines, but they are strongly recurved and not that robust. As Bernie pointed out in his paper, the most obvious comparison is with the sexually dimorphic canines of tragulids and some cervids, although evidence for dimorphism in B. fangaroo is lacking at present. Also, most diprotodontians (including thylacoleonids!) retain upper canines; they are only lost in a few groups e.g. wombats, the later and more derived diprotodontoids and some kangaroos. It's unclear whether the lower canine is retained in any diprotodontians: there are a number of unicuspid teeth between i1 and p3 in several groups, but their homologies are uncertain.

COOKE, B. N. 2000. Cranial remains of a new species of balbarine kangaroo (Marsupialia: Macropodoidea) from the Oligo-Miocene freshwater limestone deposits of Riversleigh World Heritage area, northern Australia. Journal of Paleontology, 74(2):317â326.

@ 39 - Thanks Robin, that makes sense and the name is great; associated with freshwater, hope to see images someday! I've been informed that if a kangaroo is attacked by a dingo, it will attempt to drown it in open water. I've been researching clicking in communication, and have been informed that kangaroos click orally. Are you familiar with this, and might you know whether the (single or trilled?) clicks are done with the tongue, lips, teeth or larynx?

Robin:

most diprotodontians (including thylacoleonids!) retain upper canines; they are only lost in a few groups e.g. wombats, the later and more derived diprotodontoids and some kangaroos

Really? I got that wrong then. Thanks for the correction (and for the reference). That'll teach me to generalise from an extant kangaroo's skull...

Henk was referring to 'fangaroo', a balbarine kangaroo from the Oligo-Miocene of Riversleigh

Well, the National Geographic article I looked at does refer to a 'saber-toothed' macropodid:

Henk Godthelp, a UNSW vertebrate paleontologist, says the new kangaroo discoveries include a saber-toothed species that may have used its large teeth for grooming or to attract mates.

(I'd be inclined to file that under 'mis-quoted by journalist', though.)

have all become more terrestrial AFAICT, based on digit reduction etc.

More cursorial. That doesn't mean they were semiaquatic before.

@ 42 - Yes, I don't think they were tree climbers nor as aquatic as beavers, just moving from wetland/forest swamp/ground to open dryland foraging would select for more cursorial terrestrial traits, I'd think.

Why "wetland"? Why "swamp"? Why not just simply "forest"?

We are talking about an almost global tropical/paratropical rainforest, after all.

Forest browsers tend to favor waterside openings (swamp, stream, puddle, wetland bais) within rainforests because there is an abundance of lower vegetation and/or very low canopy surrounding the water as well as floating or rooted aquatic herbaceous vegetation available year around except during the rainy season floods, when everything that can't climb trees moves upland. Most of the foliage/fruit in the undisturbed rainforest is high above the ground, inaccessible (except opportunistically) to ground feeders, except at mast drop. (Today, most rainforest is secondary growth due to holocene cutting and burning.)

Open land foragers tend to adjust to a mixed grazing/browsing diet, where the "canopy" is much lower and plentiful enough to eat, but drinking water becomes relatively inaccessible (except the rainy season), and requires migrations benefiting cursorial terrestrial adaptation. So forest ground browsers tend to associate with open water, not primarily for the water but for the lower canopy and more *available* food associated with it. But again, nothing like beavers, which have a true semi-aquatic life, dependent on the water itself, rather than the effect on the forest canopy.

Forest browsers tend to favor waterside openings

OK. But that's still not necessarily a swamp.

@ 46 - Swamp is just a name. Choose another.

Pond, lake, and river would be better descriptions. Swamp has certain important connotations- boggy waterlogged ground, large areas of standing water, an environment where swimming can be almost as important as walking- the kind of environment that encourages animals to be semi-aquatic.

And just because there was a pantropical rainforest doesn't mean there was no understory at all. AFAIK Okapis don't have any notable swimming adaptations- and they're forest dwellers, feeding on fruits and leaves in the understorey.

Dave:

AFAIK Okapis don't have any notable swimming adaptations

Indeed they don't. In this context, it is also worth noting that the rainforest-dwelling pygmy hippopotamus is less, not more, aquatic than the common hippo. (Many zoos have discovered this the hard way; they've constructed big, expensive pools in their pygmy hippo enclosures only to discover that the animals don't really utilise them that much.)

More generally, one shouldn't assume that extensive, predictable flooding is a common feature of all tropical rainforests, either now or in the geological past. Rainforest habitats are not homogenous across the world, or even across any particular continent. For example, seasonal flooding is an ecologically significant feature of the Amazonian rainforest in South America, but significant flooding is much less extensive, or hardly occurs at all, in most African rainforests.

It's worth noting that other specimens of Gobiatherium actually have ossicones atop that large nose.

Gobiatherium on Russian site : http://age-of-mammals.ucoz.ru/index/gobiatherium/0-148

I'm trying to learn something about transition between reptile and mammal, but the little problem is that I don't know what to start with, (246 or so mammals posts, and a lack of general vision of my account). Any clues?. Regards.

Susana,

I feel obliged to point out that mammals did not evolve from reptiles, instead, synapsids (mammals and relatives) and sauropsids (reptiles and relatives) share a common amniote ancestor. I'd recommend checking out Palaeos and, if you can find it, I felt the book Mammal-like reptiles and the origin of mammals by Kemp demonstrated the evolution of mammals very well (although it's probably rather dated now).

Yes, thank you, Cameron, I have found it this true afternoon. I'm not focused on the demonstration of evolution by now, as I am not biologist I don`t feel the need of ending any search talking about evolution, I am a drawer and felt more attracted to the different morphological types. Thank you again.

Susana Molina--
Wikipedia tends to have life reconstruction illustrations of its articles on fossil beasties, so, to get a beginning of an overview of what the morphotypes along the whatever-to-mammal transition looked like, you need a list of names and internet access.

If you have access to a university library (or a library where the ILL librarian is your friend), there are a couple of books from the 1980s I would highly recommend. One is T.S. Kemp's "Mammal-like reptiles and the origin of mammals" (and Kemp has a newer book that incorporates some of the same stuff with more on the later development of more modern mammals), the other is D.M. Kermack and K.A. Kermack's "The Evolution of Mammalian Charactistics." Both have readable narratives of the evolutionary sequence and a reasonable number of drawings. My personal favorite is Kermack and Kermack, which is shorter, but it doesn't have as much coverage of the variety of "Mammal-like reptiles"(*) off the direct stem of mammalian ancestry.

(*) T.S. Kemp is a real-for-real paleontologist, and if he was willing to use that term in the title of a book designed in part for use as a textbook... His younger colleagues tend not to like the term: they are more devout and puritanical in their view that only names reflecting the branching structure of the "genealogical tree" of organisms should be used. Since the currently accepted version -- this seems to be quite well established! -- is that the "reptile" (= lizard, snake, turtle, crocodile, dinosaur, bird) side of the family separated from the "Mammals and their extinct relatives" (as the Natural History Museum in New York refers to it in the floor-plan of their exhibit halls) side a LONG time ago, they don't approve of this term. "Synapsid" is the generic term for the mammal side, so the way to avoid getting lectures from people like Cameron is to say "Non-mammalian Synapsid" when you want to refer to mammal-like "reptiles."

And I second Cameron's recommendation of the Palaeos.com WWWebsite: go to the "Verrtebrates' part, then check particular parts of the vertebrate family tree. And read the essays: Toby White, who wrote most of the Palaeos.com vertebrate stuff (it started on a separate website of his own, called "Vertebrate Notes") writes well and wittlily.

Allen Hazen, thank you very much for your recommendations and detailed explanation, I take note and try to find the book, sounds truly interesting, and also good advice, I´ll call them synapsid from now on.

I´ll call them synapsid from now on

But mammals are synapsids, too.

Since the currently accepted version -- this seems to be quite well established! -- is that the "reptile" (= lizard, snake, turtle, crocodile, dinosaur, bird) side of the family separated from the "Mammals and their extinct relatives" (as the Natural History Museum in New York refers to it in the floor-plan of their exhibit halls) side a LONG time ago

Importantly, this is not new; it was already just as well established when Kemp wrote his book. All that's changing is nomenclature.

The old meaning of "reptile" is "every amniote that isn't a bird or a mammal". The new one, which some people adhere to, is "the most recent common ancestor of the reptiles-in-the-old-definition that live today, plus all of its descendants". Under the new one, Reptilia is basically a synonym of Sauropsida: the birds are now reptiles, and the "mammal-like reptiles" are not.

Me, I vastly prefer dropping the term Reptilia altogether.

Susana:

I'm not focused on the demonstration of evolution by now, as I am not biologist I don`t feel the need of ending any search talking about evolution, I am a drawer and felt more attracted to the different morphological types.

I hope you don't feel too intimidated by the science. The more you learn about the evolutionary biology that lies behind extinct animal reconstructions, the better (I dare predict) your drawings will be.

David Marjanovic yes are sypnasids, I also found it yesterday in the Wiki, and also mammals are mammals aren´t they?, I`ll keep calling them mammals, old habits die hard :).

Dartian I'm not afraid of science at all, I would very much have studied Biology - the career I mean- but I didn´t. I´m only afraid of getting into discussions about cladistic and evolution which are not my concern, biologists do it very well. Thank you so much.

The name Mammalia doesn't go away. Mammalia is a part of Synapsida; the names are not synonyms.

D. Marjanovich, it was only a joke, nada más, thank you.