Hairy Museum of Natural History

Ladies and gentlemen, step right up and don’t be shy! What you are about to see–well, it might startle you. It might shock you. It might even call into question the basic assumptions you make about the fundamental levels of goodness and decency underlying this world and all who share in it. But, as the poet said, there are indeed more things on heaven and earth than are dreamt of in your philosophy, and while the spectacle you are about to witness may seem like the dream of some fevered philosopher, no less an institution than the National Centre for Scientific Research in Paris, France vouches for the authenticity of this unprecedented display.

Shocking? Yes, but also one-hundred-percent real.

After just a few short moments of anticipatory banter, you, dear visitor, will hold before you a link to the unknown, a curiosity so curious that it defies any and all attempts by science or art to ascertain is proper classification.

Is it a recently exhumed treasure from the Orient? Is it a hideous freak of nature? Is it a long-lost record of genetic experimentation by some antediluvian race?

What contrivances have brought it before our wondering eyes this day, and how will you react in its presence? Will you be able to observe it with the dispassionate eye of the scientist, or will your curiosity turn into sheer horror as you behold its monstrous visage?

Prepare yourself, ladies and gentlemen, for what could be the most astonishing thing you will see all day. Take a deep breath, hold your clicking finger at the ready, and Behold! The fabulous Two-Headed Choristodere, ancient master of the obscure herpetological practice of Axial Bifurcation!

Further reading:

Buffetaut, E., Li, J., Tong, H., and Zhang, H. A two-headed reptile from the Cretaceous of China. Biology Letters. First cite early online publishing. DOI:10.1098/rsbl.2006.0580.

John Lynch has the story at Stranger Fruit.

And a creepy little restoration.

Update 12/23: A nice article on this and other Chinese choristoderes is up at microecos.

—Matt Celeskey.

File under: Cretaceous, Recent Discoveries, Reptiles.

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The cover of this past week’s issue of Nature is graced with a restoration of a newly discovered gliding mammal from the Age of Dinosaurs. The associated article inside describes Volaticotherium antiquum—”the ancient flying beast”—known from a flattened skeleton from the Daohugou beds in northeastern China. The fossil preserves traces of a big blob of hair and soft tissue that the authors interpret as a patagium—a large area of skin supported by the limbs that, when spread open in midleap, enabled Volaticotherium to glide through the treetops. Such gliding has evolved independently several times among mammals, in flying squirrels, for example, and colugos, and, (presumably) among the ancestors of bats.

Volaticotherium, however, hails from well before any of these aerial upstarts. The oldest known gliding rodent is not a squirrel but an eomyid from the Late Oligocene (~25,000,000 years ago), and the earliest known evidence for flight in bats comes from the Eocene, 51,000,000 years ago. Volaticotherium is at least 70,000,000 years older than that, and could be even older. (The age of the Daohugou beds is controversial, but lies somewhere between the Early Cretaceous (~125,000,000 years ago) and the Middle Jurassic (~170,000,000 years ago).) If the older age is correct, this would mean that Volaticotherium was experimenting with aerial locomotion before the 150,000,000-year-old Archaeopteryx, the earliest known bird.

Further reading:

Meng, J., Hu, Y., Wang, Y., Wang, X., and Li, C. 2006. A Mesozoic gliding mammal from northeastern China. Nature 444, 889–893. Editor’s summary.

A larger image of the cover art by Chuang Zhao and Lida Xing is shown at National Geographic News.

12/19 Update: Much more information on Volaticotherium (and how its discovery fits into the grand arc of Mesozoic Mammal Studies) in this article by Trevor Dykes.

—Matt Celeskey.

File under: Cretaceous, Jurassic, Mammals, Recent Discoveries.

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An interesting new paper recently published online in the Proceedings of the National Academy of Sciences reports on Miocene (16–19 million year old) mammal remains from South Island, New Zealand. The fossils, which consist of two jawbone fragments and the end of one femur, are surprising for two reasons:

1. These are the first terrestrial mammals known from the island nation before the arrival of humans, excepting bats (who were able to fly there),
2. The remains are tantalizingly primitive, closer in developmental “grade” to mammals that lived during the Age of Dinosaurs than most of its Miocene contemporaries.

Put together, these facts suggest that New Zealand was home to a heretofore unkown lineage of mammals that split off from the rest of the mammal-bearing world during the Cretaceous Period, when New Zealand split off from eastern Australia and began its lonely journey across the South Pacific.

The discovery of a relatively recent member of a group believed to be long extinct implies what is known as a ghost lineage—a series of ancestors whose fossils have yet to be found (or possibly were never preserved). The concept of a ghost lineage is perhaps easiest to envision in a diagram that combines a timeline with a family tree:

So here we have a grotesquely simplified family tree of mammals from the Middle Jurassic to the present day. I’ve left out quite a few critters, and I may be a bit off on some of the branching dates, but for a rough outline, it should suffice. On the right, the major players in today’s mammalian fauna, the placentals and marsupials, which split apart from each other about 125,000,000 years ago. Moving down the family tree we run into the long extinct aegialodontids, dryolestoids, and multituberculates. According to the new paper, the branch leading to the new New Zealand mammals split off before the aforementioned groups, but after earlier mammals like eutriconodonts, monotremes, and docodonts.

The dotted lines represent ghost lineages (to which I’ve added little ghosts to reinforce the point). Provided the family tree is correctly interpreted, these are paths of evolution that most certainly existed despite gaps in the fossil record. There are undoubtedly gaps in this diagram that I’ve neglected to portray, but hopefully the main points are clear.

Islands seem particularly prone to ghost lineages, perhaps because their isolated faunas often contain species whose relatives have met with extinction elsewhere in the world. Monotremes, for example, are today only found in Australia and some nearby islands. These modern-day monotremes (three species of echidna and the platypus) are island-dwelling relicts of a group of mammals that started down their own path sometime in the Jurassic Period. Geographically isolated and only distantly related to other living groups, their fossil record contains several long gaps with ghost lineages filling in the blanks. Viewed in this light, New Zealand seems like quite a likely spot to uncover a mammal with a 60 to 140 million year gap in its pedigree.

One more note about ghost lineages. The HMNH has been suffering gaps in its own record of late, and for that I apologize. (An interesting admission is that we’ve had more visitors lately than during periods of regular posting, which I hope isn’t a commentary on my writing.) Hopefully this post will mark the end of this particular ‘ghost lineage,’ and, with any luck, the Hairy Museum will regain its typical, punctuated equilibrium as we head into 2007!

Further reading:

Worthy, T. H., Tennyson, A. J. D., Archer, M., Musser, A. M., Hand, S. J., Jones, C., Douglas, B. J., McNamara, J. A., and Beck, R. M. D. 2006. Miocene mammal reveals a Mesozoic ghost lineage on insular New Zealand, southwest Pacific. Proceedings of the National Academy of Sciences USA, published online; doi:10.1073/pnas.0605684103. PDF. Press release.

Afarensis has the story, as does Palaeoblog.

And Darren Naish notes that this find inspired two earlier stories on unexpectedly long-lineaged synapsids over at Tetrapod Zoology.

—Matt Celeskey.

File under: Mammals, Neogene, Recent Discoveries.

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A post from the HMNH Curator of Ich-theology, Ray Troll:

Image by Ray Troll

Scientists have determined that the giant Devonian placoderm Dunkleosteus had one of the most powerful bites of any animal ever. This monstrous armored fish reached the size of a school bus and ate darn well anything it pleased. It’s gaping maw apparently opened at an amazing speed and was able to chomp down with astounding force. How one is able to draw conclusions like this from a pile of ancient bony plates is a bit beyond me…but hey it’s been written up in the Royal Society’s journal called Biology Letters. One thing is for sure though: Dunkleosteus was one of the wickedest looking fishes to ever swim the seas!

Further Reading:
Anderson, P. S. L., and Westneat, M. W. 2006 Feeding mechanics and bite force modelling of the skull of Dunkleosteus terrelli, an ancient apex predator. Biology Letters FirstCite early online publishing doi:10.1098/rsbl.2006.0569

The official press release.

The story at Science Daily.
An in-depth article from the Chicago Tribune.

Yahoo News has the story also.

—Ray Troll.

File under: Chordates, Devonian, Ich-Theology.

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