Paleocene Penguins

The oldest fossil penguin was discovered in the Late Paleocene, Cross Valley Formation on Seymour Island, Antarctica and recently described in the journal Geobios. Significantly larger than modern penguins, Crossvallia unienwillia contains all the hallmarks of penguin anatomy in three fragmentary bones. Most notably the preserved humerus, which reveals a very modern-looking penguin.




Claudia P. Tambussi, Marcelo A. Reguero, Sergio A. Marenssi and Sergio N. Santillana. 2005. Crossvallia unienwillia, a new Spheniscidae (Sphenisciformes, Aves) from the Late Paleocene of Antarctica, Geobios, In Press, Corrected Proof, Available online 2 August 2005.

My thoughts on Ancestor-Descendant Relationships

Following the doctrine of cladistics, the mere thought of investigating ancestor and descendant relationships was branded as a sinful act. Such orthodoxy in science needs to be over turned and a new generation of scientists are attempting the forbidden act. Benoit Dayrat, a scientist who has published on botany and fossil snails wrote a brilliant, if someone historical, call to arms for paleontologists to launch investigations into ancestor-descendant relationships. "Ancestor-descendant relationships [sic] should be studied as often as possible because they are more accurate representations of the evolutionary history than sister-group relationships." p. 351, and later "Ancestor-descendant relationships should be investigated as often as they can be." p. 352. (Dayrat, 2005).



However, before such investigations can be launched there is the slight problem of how one goes about searching and proving ancestor-descendant relationships. There are basically three schools of thought. ONE, use stratigraphy to accept or reject various most parsimonious trees or TWO, include the stratigraphic relationships within the data somehow, or THREE use a phenetic approach of comparing morphology through time. While not offering a solution to which is method is most appropriate, Dayrat concludes that the best way of depicting the evolutionary history is by a "tree of life" and hierarchical classifications fail miserably at conveying useful information.




Dayrat, Benoit (2005) Ancestor-descendant relationships and the reconstruction of the Tree of Life Paleobiology 2005 31: 347-353.

Closing the gaps in the origin of tetrapods

An increasing number of Late Devonian tetrapods have emerge from various localities and environments throughout the world. Just twenty years ago, all we knew of the transition of vertebrates from the water to land was the fossil Ichthyostega from Greenland. Today, 17 distinct Late Devonian tetrapod forms are known, including 9 named genera from 9 different individual localities worldwide. An article in press by Jennifer A. Clack, in Palaeogeography, Palaeoclimatology, Palaeoecology, nicely sums up all that we known of these new forms. One thing caught my attention in the article. Clack presents a novel idea concerning the way in which the first tetrapods may have walked on land. Previously, most people conjectured that early tetrapods medially-laterally "slittered" out of the water. But Clack, presents the idea that early tetrapods dorsally-ventrally "inch-wormed" out of the water based on the morphology of the vertebrate. Further investigation is required.


Jennifer A. Clack, The emergence of early tetrapods, Palaeogeography, Palaeoclimatology, Palaeoecology, In Press, Corrected Proof, Available online 8 September 2005.

Images of Katrina

This entry is not related to vertebrate paleontology. I saw this image on the NOAA website, and thought it captured the destruction of New Orleans, in one image.

Fossil chimpanzee, and now we know it all.

	Strangely, in this week's issue of Nature, scientists present two discoveries that seem like they should be juxtaposed in time; the complete sequencing of chimpanzee DNA and the first discovery of a fossil chimpanzee. That is right! Until this week there have been no reported fossil chimps discovered. This absence of chimp fossils has been tricky to explain, especially since so many early human fossils have been discovered. Sally McBrearty and Nina Jablonski offer a reason; fossil chimps likely were restricted to woodland habitats and did not venture into the savannas like our early ancestors. Such a habitat difference has lead to a bias in the fossil record. The oldest fossil chimp is an assemblage of three teeth discovered from the Kapthurin Formation in Kenya and are around 500,000 years old. This same formation has produced specimens of Hominin fossils attributed to Homo erectus or Homo rhodesiensis.
McBrearty, S. and Jablonski, N. G. 2005. First fossil chimpanzee. Nature 437, 105-108 (1 September 2005) | doi: 10.1038/nature04008