Posts Tagged ‘triassic’

Minimalism as a trope in Early Triassic cephalopod artistic traditions

10 October 2011

The recognition that Shonisaurus death assemblages preserved in the Late Triassic aged Lunning Formation represent large-format self portraits created by hyper-intelligent Kraken like cephalopods marks the beginning of a dramatic paradigm shift in paleontology. This break-through insight requires cold reappraisal of 200 years of research and a thorough re-imagining of more than 200 million years of evolutionary history. Here, we report surprising evidence that minimalist artistic traditions were already deeply entrenched among cephalopod artists by the late Early Triassic. A single small ichthyosaur vertebrae set in a lime mud matrix confronts the viewer with ambiguous questions about mortality, corporeality, decay and emptiness. Although the precise social context of this work remains unclear, perhaps the single bone was placed in an unusual setting that undermined the “authenticity” of the piece, and underscored the inherent absurdity of art à la Duchamp’s Fountain (1917).

It seems surprising that this abstracted form antedates the highly figurative I, Kraken piece which dates to the earlier late (or perhaps later early) part of the Late Triassic. Assuming this work of understated irony is  a response to bourgeois excess, widely emulated figurative traditions must have been developed by the Permian. Alternatively, perhaps the historical trajectory of of cephalopod aesthetics followed a very different course than that of 20th Century Western societies (human). The identification of  hyper-minimalist tropes approaching the Suprematism of Malevich or the early works of Rauschenburg, could help to better establish the temporal polarity of the evolution of aesthetic movements in Mesozoic (and even Paleozoic) cephalopod art.  Thus particular attention should be paid to works of cephalopod art that show no clear signs of being “made,” whether they be barren bedding planes, massive mudstones entirely devoid of fossils, or even paraconformities.

Tanystrophic Theatrics

21 July 2009

…with apologies to the Theatrical Tanystropheus.  Lots of “work” to keep me “busy” and away from “blogging” this “summer.”  But I did return from Europe with a steamer trunk of full of chocolate, some knives, and a shit-ton of pictures–so I’ll try to post a steady trickle of the latter over the next few weeks.

Ah, Tanystropheus: proof that the Creator has either a sense of humor or a cannabis habit.  Tanstropheus seems to be the only protorosaur that gets any play and generally I’m loathe to reinforce such hegemony, but one must admit the dude is wholly protarded in the best possible sense of the word.

While perhaps a bit out of date–and arguably biomechanically impossible–these diorama reconstructions at least convey to the museum visitor to check it: some crazy-ass critters called this planet home in the past. You can pierce your labrum, or whatever, but basically your species is pretty weakly conventional. Srry.

Grenzexcuseszone

15 June 2009
Nosediver

Hescheleria by Zach Miller.

Granted, this is a cop-out.  I’m in the airport, on my way to meet Hescheleria and friends.  Hard to believe it has been over a year (well over in fact) that Zach sent me this drawing for use in my now infamously nonexistent post on thalattosaurs.  Perhaps by the time I get back I will finally have something interesting to say about these, the enigmaticist of hellasaurs–you know, anything could happen.

In the meanwhile, go check out the latest edition of the Boneyard over at Zach’s blog.  See you in a few weeks!

I Support Scientific Triassicism

31 December 2008

If 2008 is remembered for anything, surely it will come to be known as the year Triassic broke.

When you were a kid, the Triassic was an impossibly dreary place peppered with some generic economy-model dinosaurs.  Oh sure there were also some stupid looking synapids, a bunch of “thecodonts” and “eosuchians” or whatever, a mess of footprints, maybe a mass extinction event or two…but honestly, who gave a Morganucodon‘s ass?

I mean, check out the short shrift the Triassic gets in Zallinger’s famous Age of Reptiles mural. “Dude, is that a Plateosaurus?  No way…sick!”

click to buy the t-shirt!

While Triassic dinosaur faunae may not be as a charismatic as those of the later Mesozoic, there are still plenty of reasons to be interested in what was going on on our planet between ~250 and ~200 million years ago.  Emerging from wake of the largest mass extinction event of all time, perhaps uncoincidentally, the Triassic was a time of dramatic evolutionary change.  A great wealth of new clades appeared in the Triassic–including the first “true” mammals, crocodilians, frogs, turtles, squamates, dinosaurs, pterosaurs, ichthyosaurs, sauropterygians, scleractinian corals, modern sharks, coccolithophores, several important insect groups, I could go on and on–this evolutionary overdrive is so pronounced that some even speak of a “Triassic explosion.” The end of the Triassic was marked by another pronounced extinction event, which although pale in comparision to the Permo-Triassic event may have paved the way for the rise of the dinosaurs although others maintain it was the rise of dinosaurs themselves that drove the extinction.

All of which makes this classic Onion article even more hilariously poingnant.  In fact, we “secular Triassicists” are witnessing something of a golden era.  Nick Fraser’s spectacular Dawn of the Dinosaurs, published in 2006 is a great resource for those interested in delving into the Triassic world, as visualized by the exceptionally talented Douglas Henderson.  However the pace of discovery and the renewed scientific interest in the Triassic is so pronounced that a revised edition is already needed.

In the mean time, here is my list of the top 5 Triassic news stories of 2008:

click to buy the t-shirt!

5) The Aeto-Contra scandal – The confusion and controversy surrounding the naming of a new species of the unusual armored hellasaurs known as aetosaurs exploded across the internets in early 2008 and blossomed into a full fledged “-gate” with its own website and everything.  While in the end, the “resolution” of the conflict left plenty to be desired, if it’s true that there is no such thing as bad publicity then perhaps the silver-lining to the scandal is a somewhat higher profile for those wacky Aetosaurs.

4) Kryostega the Crocomander and Gerrothorax the, uh, Toiletmander? – While large, freakazoid “amphibians” (i.e. non-amniote tetrapods) were diverse and widespread in the Paleozoic they gradually trickled out during the Mesozoic leaving only the extant lissamphibians.  However during the Triassic a number of impressive “amphibians” were still around kicking ass and taking names.  The antarctic Kryostega a 4.5 meter aquatic predator was in the news this year, as was the rather smaller Gerrothroax whose unusual head-lifting bite inspired some choice wordsmithing by headline writers across the globe.  Don’t miss Matt Celeskey’s awesome interactive Gerrothorax animation at the Hairy Museum of Natural History. (Speaking of Antarctica, the oldest known tetrapod burrows, sweet.)

3) Longisquama Lets its Freak Flags Fly – Even among the surreal host of Triassic creatures, Longisquama stands out as a weirdo.  Recent work on the bizarre skin appendages of Longisquama add to our understanding of this strange animal but still leave much room for future discovery…more on this later, maybe.

2) The Triassic (Blog) Explosion – No fewer than three, that’s right three Triassic themed blogs launched this year all of which are required reading for Triassophiles:

Life of the Madygen – triassiccritters.blogspot.com – Written by a paleontologist based in Germany, this blog highlights the important Triassic fossils of Central Asia, including the aforementioned Longisquama.  The outcrop photos are geo-porn at its finest.

Chinleana – chinleana.blogspot.com – The Chinle Formation is the most famous and arguably most important source of terrestrial Triassic fossils in North America.  Recent discoveries in the Chinle have shed light on the origin of dinosaurs, transformed our understanding of late Triassic stratigraphy and revealed a host of interesting hellasaurs all of which (and more) are fodder for Chinle expert Bill Parker.

Paleoerrata – paleoerrata.blogspot.com – Yet another expert on North American Triassic terrestrial vertebrates, Jeff Martz’s blog thus far has covered not just the evolutionary history of the Triassic but is also a font of wisdom for aspiring young bucks and does, er, un- or underemployed paleontologists.

1) Triassic Turtle ManiaOdontochelys and Chinlechelys: a one-two punch in the ongoing turtle evolution cage-match.  Confusingly each fossil is seen as a TKO by the respective rival camps, on the plus side both paint a picture of Triassic turtles as being more morphologically and ecologically diverse than ever imagined.  Both fossils sent ripples across the blogosphere as usual, the Hairy Museum of Natural History is an excellent place to start.

Coming in 2009 – The Return of the Enigmatic Hellasaur (including Thalattosaurs…I swear!).  See you next year!

Enigmatic Triassic Hellasaur Thursday — The mostest unkindestest cut

8 August 2008

Venom–toxic fluid injected to subdue prey or deter potential predators–is widespread in the animal kingdom, from jellyfish to scorpions to platypodes. A case could even be made that stinging nettle is an example of a venomous plant, since it injects its toxin into victims. However, most toxic plants, as well as toxic animals and fungi that rely on passive delivery of toxins (e.g. newts) are considered poisonous but not venomous.

Snakes are one of the most familiar groups of venomous animal although a majority of snakes lack venom. Most people are also aware of the venomous beaded lizards (or, “gila monsters”) in the genus Heloderma. Far less well known is that varanid monitor lizards and bearded dragon, Pogona, popular in the pet trade, also possess a mild venom. We’re talking real venom here, not the bacterial brew that produces the much discussed septic bite of some varanid lizards. In fact, the discovery that venom occurs in reptiles aside from snakes and Heloderma was made only a few years ago and has forced us to rethink the evolutionary origins of venom among squamates (Fry et al. 2006).

So, what does any of this have to do with enigmatic Triassic hellasaurs? Read the rest of this entry »

Enigmatic Triassic Hellasaur Thursday…who’s counting anway? — The Duck-billed Ichthyopus

8 May 2008

When George Shaw received the first platypus skin to make it to England in 1789, he took a pair of scissors to it to look for stitches, or so the story goes. It is impossible not to entertain some doubts as to the genuine nature of the animal,” wrote Shaw. Surgeon, and racist, Henry Knox argued that the Asian itinerary by which the specimen had traveled was, “sufficient to rouse the suspicions of the scientific naturalist, aware of the monstrous impostures which the artful Chinese had so frequently practiced on European adventurers.” Of course, the reality of this chimerical creature has long since been recognized, and, as of this week, we have the unique genome to prove it.

More recently the Archaeoraptor” scandal raised echoes of Knox’s Sinophobia, and this weeks’ hellasaur is certainly enough to raise eyebrows. Hupehsuchus nanchangensis, has that “designed by committee” look, with the limbs of a basal ichthyosaur, the dorsal armor of a placodont and the bill of a…well, duck. But the fossils indeed check-out: this is no “monstrous imposture”, just one freaky-ass (or if you rather, enigmatic-ass) hellasaur.

Hupehsuchus drawing by Zach Miller

Hupehsuchus nanchangensis by Zach Miller

And the more you look, the weirder it gets…more tomorrow!

Enigmatic Triassic Hellasaur Thursday: Part the, um fourth?, Kyrgyz Kameleon

17 April 2008

If you’re hoping to make it into the fossil record, being a small, arboreal insectivore is probably not the best way to go. Forest soils are veritable compost heaps: acidic and crawling with critters and fungi that would happily mill your remains to humus given half a chance. And your scrawny, flexible skeleton is highly unlikely to endure the vicissitudes of long distance transport to some more suitable sedimentary environment.

Of course if you’re reading this blog chances are good that you’ve already been born so it may be too late to fix this. But don’t worry–there is a back up plan: find a lake, and fall in. Hey, it worked for Longisquama and Sharovipteryx, though a case could be made that they would have saved everyone a lot of trouble if they had just rotted on the forest floor like a respectable forest dweller.

Landsat

The Triassic Madygen Formation of Kyrgyzstan is among the most important sources of Triassic insect fossils in the world (Fraser 2006). In fact, I’d almost rather write about the titanoptera, an “enigmatic” insect group which included the 30-cm wing-spanned Gigatitan vulgaris that may have looked something like the result of an unholy love-affair between a coackroach and a mantis…on crack. But this is “Hellasaur” Thursday so I’d better stay focused.

Left: LANDSAT image of Madygen Formation outcrops – de.wikipedia

In fact, it was the search for insect fossils that led to the discovery of two the Triassic’s more problematic hellasaurs. The first, Sharovipteryx mirabilis, is bad enough, what with its bizarre hind-limb “delta wing” and its purported link to pterosaur evolution despite its patagium-backward construction. We’ll leave Sharovipteryx be for now because our topic at hand is going to require the full bottle of Excedrin.

Longisquama insignis type specimen.

Behold, Longisquama insignis, “remarkably long-scaled” as the rather prosaic scientific name would have it. “Remarkable” is certainly *one* way to describe Longisquama. Whether the protarded 10 to 15 cm long structures which appear to project from its back are scales is (as Zach noted in the comment to a previous post) up for debate.

Some argue that the strange frond-like structures are the foliage of some unknown plant. They do look vaguely vegetative, although other plant matter on the slab appears to show a very different style of preservation and Fraser notes that they have “a peculiar venation pattern that is inconsistent with any known Triassic foliage types. The structures certainly appear to be physically associated with the skeleton itself, and most who have examined the fossil seem to accept that they belong to the skeleton, though the ‘consensus’ ends abruptly there.

One camp holds that they are feathers (which are, of course, modified scales) (Jones et al. 2000)! If this were true it might seriously upset the notion that birds are derived theropod dinosaurs. However, this view is a decided minority and a vast array of other skeletal evidence as well as the preservation of far more convincing feathers on some theropod fossils weigh heavily in favor of the birds-as-dinosaurs hypothesis. That is, unless maniraptoran theropod “dinosaurs” are secondarily flightless birds that merely look like dinosaurs….

Oregon State University

Anyway, if the nature of these structures remains contentious, then establishing their function has basically been an interpretive free-for-all. A number of authors have tried to turn them into a parachuting or gliding apparatus of some sort. However, unless they supported a membrane, or were filled with helium, it’s hard to imagine how this would have worked. That said, a recent phylogenetic analysis suggests Longisquama may have been closely related to Coelurosauravus a Permian diapsid with a slightly more (though perhaps not altogether) convincing gliding membrane projecting from its sides.

Left: Longisquama as plumulus glider – Oregon State University.

Display –either to attract mates or perhaps to scare off potential predators or intraspecific rivals—is another popular explanation and probably a more convincing one. Elongate plumes in birds are exclusively a sexual selection affair; in fact their value as a sexual symbol may be directly linked to their hindrance to locomotion.

Scissor-tailed FlycatcherTyrannus forficatus

Another, admittedly fanciful, scenario is that the resemblance to a plant frond is not-coincidental. Could the scales of Longisquama be some extreme cryptic adaptation? Perhaps they hid the animal from predators or provided cover allowing Longisquama to ambush its supposed insect prey? Structural mimicry of plants is rampant among arthropods and in addition to more familiar cryptic coloration patterns, a number of land vertebrates use posturing as well as modified skin surfaces to blend into their surroundings

While sexual advertising and cryptic camouflage would appear to be at odds with one another there are animals well-equipped for both. Notably, for our purposes, chameleons, who are at once exceptionally cryptic and at the same time often sport elaborate sexual signaling structures like horns and crests. While chameleons probably don’t adjust their colors to match their background as popularly believed, color switching does allow them to temporarily display their mood to another individual then switch back to their more cryptic “normal” coloration when the mood has passed.

Oregon State University

To continue our cautious, chameleon-like walk out on a very thin limb, it’s interesting to note that Longisquama’s skull, as figured by Senter (2004) (shown left), bears a remarkable superficial similarity to that of a chameleon [Note that other, very bird-like reconstructions of the skull out there are probably inaccurate, especially with regards to the supposed antorbital fenestra which is likely a preservational artifact]. The skull of Longisquama’s cousin Coelurosauravus is perhaps even more chameleon like. I’m not prepared to make an argument for functional convergence here, but to me the resemblance is quite striking.


Longisquama by Matt Celeskey

Longisquama is certainly not closely related to chameleons, but its probable close relatives the enigmatic hellasaurs known as drepanosaurs, have been inferred to have had a chameleon-esque lifestyle. One wonders if this interpretation might be extended to Longisquama. Was it lurking in the Triassic treetops, flashing chromatophoric signals across its crazy dorsal scales and snagging titanopterans with a ballistic tongue?

Left: Longisquama by Matt Celeskey

Or, have I just been out in the sun to long?

refs-

Fraser, Nicholas 2006. Dawn of the Dinosaurs Indiana University Press

Jones, Terry D. et al. 2000. “Non-avian Feathers in a Late Triassic Archosaur.” Science 23 June 2000:
Vol. 288. no. 5474, pp. 2202 – 2205 DOI: 10.1126/science.288.5474.2202

Senter, Phil 2004. “Phylogeny of Drepanosauridae (Reptilia: Diapsida).” Journal of Systematic Palaeontology 2: 257-268 DOI: 10.1017/S1477201904001427