Fish Out of Water Almost 20 Million Years Faster

There is also the issue of whether the evolution to tetrapod from fish occurred once or several times. Seeing as we see existing organisms with mobile ability in tidal mud flats it is not unreasonable that such adaptation to a new opportunity occurred several times.Enjoy.

---

I love this tidbit

quote:

---

An undetermined species of tetrapod (illustrated) created tracks in what's now a Polish quarry (bottom), a new study says.

---

How can you illustrate something that is undetermined (and why does it look like tiktaalik?)Enjoy.Edited by RAZD, : color

Hi Iblis,Here's the Nature issue:Muddy tetrapod origins | Nature

quote:

---

​

Palaeontology: Muddy tetrapod origins p40

​

The tracks left by organisms are among the most difficult of fossils to interpret. But just such evidence puts debate about the origins of four-limbed vertebrates (which include ourselves) on a changed footing.

​

Philippe Janvier & Gal Clment

​

Abstract

​

The tracks left by organisms are among the most difficult of fossils to interpret. But just such evidence puts debate about the origins of four-limbed vertebrates (which include ourselves) on a changed footing.

​

The term 'tetrapodomorph fishes' scarcely rolls off the tongue, but these are fossil animals that have a special place in the evolutionary history of vertebrates. It was through the stepwise transformation of paired fins in this lineage of lobe-finned fishes that paired limbs with digits arose, marking the advent of the four-limbed vertebrates, or tetrapods.

​

1. Philippe Janvier and Gal Clment are at the Musum National d'Histoire Naturelle (CNRS UMR7207), 8 rue Buffon, 75231 Paris Cedex 05, France.

​

Nature 463, 40-41 (7 January 2010) | doi:10.1038/463040a; Published online 6 January 2010

​

Tetrapod trackways from the early Middle Devonian period of Poland p43

​

The earliest body fossils of tetrapods (vertebrates with limbs rather than paired fins) date to the Late Devonian period. There have been claims of tetrapod trackways predating these body fossils but the age and identity of the track makers have remained controversial. The discovery of well-preserved and securely dated tetrapod tracks from Polish marine tidal flat sediments of early Middle Devonian age, around 18 million years older than the earliest tetrapod body fossils, is now presented.

​

Grzegorz Niedźwiedzki, Piotr Szrek, Katarzyna Narkiewicz, Marek Narkiewicz & Per E. Ahlberg

​

Tetrapod trackways from the early Middle Devonian period of Poland

​

Grzegorz Niedźwiedzki1, Piotr Szrek2,3, Katarzyna Narkiewicz3, Marek Narkiewicz3 & Per E. Ahlberg4

​

1. Department of Paleobiology and Evolution, Faculty of Biology, Warsaw University, 2S. Banacha Street, 02-097 Warsaw, Poland
2. Department of Paleontology, Faculty of Geology, Warsaw University, 93 Żwirki i Wigury Street, 02-089 Warsaw, Poland
3. Polish Geological Institute, 4 Rakowiecka Street, 00-975 Warsaw, Poland
4. Subdepartment of Evolutionary Organismal Biology, Department of Physiology and Developmental Biology, Uppsala University, Norbyvgen 18A, 752 36 Uppsala, Sweden

​

Abstract

​

The fossil record of the earliest tetrapods (vertebrates with limbs rather than paired fins) consists of body fossils and trackways. The earliest body fossils of tetrapods date to the Late Devonian period (late Frasnian stage) and are preceded by transitional elpistostegids such as Panderichthys and Tiktaalik that still have paired fins. Claims of tetrapod trackways predating these body fossils have remained controversial with regard to both age and the identity of the track makers. Here we present well-preserved and securely dated tetrapod tracks from Polish marine tidal flat sediments of early Middle Devonian (Eifelian stage) age that are approximately 18 million years older than the earliest tetrapod body fossils and 10 million years earlier than the oldest elpistostegids. They force a radical reassessment of the timing, ecology and environmental setting of the fish—tetrapod transition, as well as the completeness of the body fossil record.

​

Nature 463, 43-48 (7 January 2010) | doi:10.1038/nature08623; Received 21 July 2009; Accepted 29 October 2009

---

Enjoy

---