Dinosaur Legs in Motion

Every little kid who has stared up at a skeleton of Tyrannosaurus rex has envisioned the creature running, slashing its giant jaws and roaring in the Mesozoic air. However, scientists are not afforded such liberal imaginations, and must stick with the facts. And the facts are just bones. A recent article in this weeks Nature, takes a look at three possible styles of reconstructing Tyrannosaurus rex. Take a look at the animations, and see how really different the possiblities really are!


Hutchinson, JR and Gatesy, SM (2006) Dinosaur Locomotion: Beyond the bones. Nature 440, 292-294 (16 March 2006) | doi:10.1038/440292a

Animations

A new living species of mammal part of an ancient lineage.

Diatomyid rodents have thought to have been extinct for the last 11 million years. They are basal hystricognath rodents (a group that later diversified in South America). A recently described living rodent from the limestone karsts of Laos, gives amble data to enable scientists to figure out the troublesome relationship between Ctenodactylidae and Hystricognatha rodents. Mary Dawson, the eminent rodent paleontologists at the Carnegie Museum, and colleagues resigned the new living rodent to the fossil family after reading the initial description made by Paulina Jenkins and colleagues at the The Natural History Museum in London.


Dawson, M.R., Marivaux, L., Chuan-kui Li, Beard, K.C. and Metais, G. (2006). Laonastes and the "Lazarus Effect" in Recent Mammals. Science 311: pp. 1456-1458.


Jenkins, P.D., Kilpatrick, C.W., Robinson, M.F., and Timmins, R.J. (2005) Morphological and molecular investigations of a new family, genus and species of rodent (Mammalia: Rodentia: Hystricognatha) from Lao PDR. Systematics and Biodiversity 2(4):419-454.

Ugh! Fossil Poop with Impression of Foot Print.

I would have hardly thought that the swished dog poop on the sidewalk could somehow be preserved in the fossil record; complete with the imprint of someone's shoe, but that is exactly what happened to several fossil poop specimens (coprolites) from the Miocene of Lisbon. Miguel Telles Antunes and colleagues present not just one example of this event occurring, but several. The likely producer of the poop, Anchitherium, an ancient horse, also was the "victim" of a misguided step. Another specimen however, was likely produced by Brachyodus, but stepped on by the ancient deer, Procervulus.

Antunes, M.T., Balbino, A.C., and Ginsburg, L. 2006. Miocene Mammalian footprints in coprolites from Lisbon, Portugal, Annales de Paléontologie, In Press, Corrected Proof, , Available online 2 March 2006.

I wonder what Nick thinks of Dr. Ji's newest Discovery

A couple years ago, I can across Nick Longrich hiding in the labyrinthine fossil collections of the American Museum of Natural History. He had before him a colossal amount of bone scrap and miscellaneous fossils from the Hell Creek Formation. Inquisitively I asked him what he was looking. He was looking for caudal (tail) vertebrae of a Mesozoic mammal, which he believed showed adaptations for swimming. I thought the idea was interesting, but a bit conjectural. I helped him out by finding more cartons of bone scrap to examine. Nick later when on to present his findings at the Society of Vertebrate Paleontology meetings in 2004.




The cover of last week's Science magazine features a reconstruction of a Mesozoic mammal Castorocauda from the middle Jurassic of China. It is specialized aquatic swimmer with a scaly tail similar to river otter's tail. Castorocauda is a docodont, a group of mammals that specialized in an omnivorous diet with complex molar anatomy. The skeleton also preserves the oldest record of mammal fur, and indicates that Mesozoic mammals were much more diverse then previously believed.


Longrich, N. 2004. Aquatic specialization in mammals from the Late Cretaceous of North America. Journal of Vertebrate Paleontology, vol.24, no.3, Suppl., pp.84-85.


Ji, Q., Luo, Z-X, Yuan, C-X, Tabrum, A. 2006. A Swimming Mammaliaform from the
Middle Jurassic and Ecomorphological Diversification of Early Mammals. Science, vol. 311 p. 1123-1127.

Single Tooth Sheds Light on Early African Diversity

Fossil vertebrates from the early Cenozoic of sub-saharan Africa are known from only a handful of sites. In this month's Journal of Paleontology, Nancy Stevens and colleagues describe a single tooth of an endemic family of African rodents called Phiomyidae. It comes from a new microvertebrate site in southwestern Tanzania from the Rukwa Rift Basin, and is believed to be middle Eocene to early Oligocene in age. Phiomyid rodents are best known from Eocene and Oligocene deposits in Egypt. This specimen demonstrates other early Cenozoic fossil vertebrates from sub-saharan Africa maybe forthcoming.

Stevens, N.J., O'Connor, P., Gottfried, M.D., Roberts, E.M., Ngasala, S., and Dawson, M.R. 2006. Metaphiomys (Rodentia: Phiomyidae) from the Paleogene of southwestern Tanzania. Journal of Paleontology 80(2):407-409.