Nature Blog Network

Friday, August 29, 2008

Who's got the oldest?

In my post about harvestmen, I mentioned the ancient fossilized penis found in 2003, that dated back 400 - 412 million years ago. Unfortunately, I forgot the Dec, 2003 publishing of an even older specimen of male genitals. In Herefordshire England, 425 mya, an ostracod was buried in volcanic ash during the Silurian Period and quickly mineralized, preserving even the soft tissues.

Originally in Science: 10.1126/science.302.5651.1645

Colymbosathon eclecticos, Greek for "Amazing swimmer with a large penis", could easily be mistaken for a modern ostracod, so similar is the morphology. Like the harvestman example before, this indicates a group with a basic body plan (and even much of the detail) that has shown very little change over a 400+ million year period. Ostracods are well known in the fossil record back to about 500 mya. From this find they have been relatively stable for almost the entire time.

It also shows two examples (one terrestrial, one marine) of male copulatory organs from the late Silurian–early Devonian periods. In the ostracod this is especially interesting as it extends the identification of specific gender in a group that is very common in the fossil record, but for which previous gender identification was only to the Cretaceous Period (65–145 mya).

Not to leave the lady inverts out, where there is a male copulatory organ there hopefully can be found a receptive female. It took the same team a few years to process and publish the finding of a female ostracod from the same area, known as the Herefordshire Lagerstätte. The unique thing about this new fossil ostracod ? Hint the new species name is Nymphatelina gravida.

Like C. eclecticos, this ostracod was found in the Herefordshire Lagerstätte and her soft organs were remarkably well preserved, including her eggs. When the team used their grinding and 3D reconstruction technique, they discovered what appears to be a brood of some 20 eggs preserved in her shell. The same brooding is observed in modern ostracods, such as the modern Gigantocypris dracontovalis pictured below the 3D reconstruction of N. gravida. Another remarkably conserved body plan and biological behavior (parental brooding).

Oh, Nymphatelina gravida translates roughly to "young pregnant ocean guardian woman."

Top is digital reconstruction of N. gravida brooding it's eggs (yellow), bottom is the modern ostracod G. dracontovalis also brooding.
Original image from University of Leicester

Update: Todd has reason to ask "Who has the oldest" of C. eclecticos as well, the oldest ostracod eyes in Ostra-blog 4.


D. J. Siveter (2003). An Ostracode Crustacean with Soft Parts from the Lower Silurian Science, 302 (5651), 1749-1751 DOI: 10.1126/science.1091376

David J. Siveter, Derek J. Siveter, Mark D. Sutton, Derek E.G. Briggs (2007). Brood care in a Silurian ostracod Proceedings of the Royal Society B: Biological Sciences, 274 (1609), 465-469 DOI: 10.1098/rspb.2006.3756

Mark D. Sutton, Derek E. G. Briggs, David J. Siveter, and Derek J. Siveter (2001). Methodologies for the Visualization and Reconstruction of Three-Dimensional Fossils from the Silurian Herefordshire Lagerstätte. Palaeontologia Electronica, 4 (1)

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