The science blogs have been abuzz with news of the Middle Devonian tetrapod tracks from Zachełmie, Poland, which apparently pre-date the first tetrapod body fossils by 18 million years (conventionally speaking) and even elpistostegids such as Panderichthys and Tiktaalik by 10 million years (Niedźwiedzki et al. 2010). This is certainly a discovery with “wow factor”. There have been previous claims of tetrapod tracks pre-dating the body fossils, but this is the first with really secure stratigraphic constraints. Brian Switek sounds a cautionary note, wondering whether the Polish tracks might be impressions made by fins with digit-like extensions, but Ed Yong notes that Jenny Clack, who has seen the tracks at firsthand, seems pretty convinced of their tetrapod origin. It’s also interesting, I think, that these tracks are in marine sediments. If the bizarre ‘fishapods’ of the Devonian were really semi-aquatic denizens of floating forests that extended out over the pre-Flood oceans, as Kurt Wise (2003, 2008) has proposed, this association with the marine environment is significant.
In other news, the speed at which the Mediterranean Basin was filled with water following the Messinian salinity crisis is being re-evaluated. Subsurface erosion features, previously attributed to the action of rivers, have been reinterpreted by Garcia-Castellanos et al. (2009) as the product of catastrophic flooding. This research suggests that 90% of the basin might have been filled in a short period ranging from a few months to two years, and that sea level rise during the event might have peaked at >10 metres per day. This adds to a growing list of large-scale overspill floods during the Cenozoic, including those associated with the Ebro Basin, Lake Agassiz, Lake Missoula, Lake Bonneville, and the English Channel.
Garcia-Castellanos D., Estrada F., Jiménez-Munt I., Gorini C., Fernàndez M., Vergés J., De Vicente R. (2009). Catastrophic flood of the Mediterranean after the Messinian salinity crisis. Nature 462:778-781.
Niedźwiedzki G., Szrek P., Narkiewicz K., Narkiewicz M., Ahlberg, P. E. 2010. Tetrapod trackways from the early Middle Devonian period of Poland. Nature 463:43-48.
Wise K. P. 2003. The pre-Flood floating forest: a study in paleontological pattern recognition, in: Ivey R. L. Jr. (editor), Proceedings of the Fifth International Conference on Creationism, Creation Science Fellowship, Pittsburgh, pp.371-381.
Wise K. P. 2008. Sinking a floating forest. Answers 3(4):40-45.