Permian Fossils Finds in Taylor County Plentiful

Millions of years ago, Taylor County was a far different place, one recorded in its fossil record.

Now, some of that once-forgotten history is documented in a recent paper published in the Journal of Paleontology.

The area is rife with finds from the Permian, a geological era that began roughly 290 million years ago, long before even the dinosaurs, and lasted for roughly 47 million years.

The recent paper, titled “Faunal overview of the Mud Hill locality from the early Permian Vale Formation of Taylor County, Texas,” details a “previously undescribed" area near Abilene, "the first vertebrate-bearing locality from the (Vale) formation to be described in detail in several decades."

The paper was written by Bryan M. Gee, Diane Scott, and Robert R. Reisz of the Department Biology with the University of Toronto Mississauga, along with Steven J. Rosscoe of the Department of Geology of Hardin-Simmons University, and Abilene fossil-finder Judie Ostlien. It notes that the site features “juvenile diplocaulids, captorhinids, abundant material of rare taxa such as varanops and diadectids,” and a first report of a “recumbirostran ‘microsaur’ from the formation" among its finds.

Red bed revolution

During the Permian era, Abilene would have been very near the equator and on the interior of the massive supercontinent called Pangaea, said HSU's Rosscoe.

"The climate was extremely dry and very warm — warmer even than we can imagine in the hottest of our summers in recent years."

Early amphibians and reptiles inhabited small scattered shallow bodies of water on a vast gently sloping land surface.

"Most of the time that surface was bone-dry, but in rare rains water would flood over the surface moving bigger particles and depositing them in thin layers over the pre-existing surface," he said.

The earliest reported collection of significant material from what is known as the “Vale Formation” was from 1939-40 on the land of C.O. Patterson near Lawn, under the direction of a Works Projects Administration excavation led by the University of Texas.

A paper published in 1953 by John Andrew Wilson of the University of Texas says "several specimens of well-preserved paleoniscoid fishes and a large quantity of plant material were discovered," as well as well-known fossils of Permian-age creatures including Diplocaulus, Seymouria, and the famous, fin-backed Dimetrodon.

The distinctive Permian ecosystem described by the most recent paper, made up of fossils located near Buffalo Gap, was first uncovered by Judie Ostlien, Jo Helen Cox, and Robert Burt, a number of years ago.

Some of their initial finds were featured in the Grace Museum's "Dinosaurs of Texas" exhibit in 2003-04, and certain of those first fossils have gone on to a wide degree of fame.

For example, a well-articulated fossil of a varanops, a pelycosaur that – at its largest – was about the size of modern monitor lizards, became the subject of a 2006 paper published in the Journal of Vertebrate Paleontology, “An Articulated Skeleton of Varanops with Bite Marks: The Oldest Known Evidence of Scavenging among Terrestrial Vertebrates.”

The latest paper on Taylor County's fossil record, using fossils primarily collected by Ostlien and her father, Dale Ostlien, describes what is believed to be a pond deposit, which organisms were believed to have been preserved "in situ," essentially the place where they died.

"Most of what we know from the Permian of Texas comes from floodplain deposits that were formed in relatively high-energy settings (e.g., rivers) that led to skeletons being transported for some distance and becoming entirely disarticulated," wrote Bryan Gee, the paper's primary author, in an email.

The most common animals found in such deposits are large, aquatic to semi-aquatic amphibians, freshwater sharks, and "carnivorous synapsids,” reptilian precursors to mammals, Gee said.

"What we see at the Mud Hill locality is the preservation of a very different setting," he said.

Analysis of the rocks in which the fossils were preserved also tells us that the animals were preserved in a "low-energy setting, with very little transport, and were exposed to the surface for a long time," he said.

The only aquatic animals are very small, juvenile forms of the aquatic amphibians, Gee said.

“There are abundant remains of a large herbivorous almost-reptile (diadectids), and some of the skeletons are still neatly articulated,” he said. “What all of this tells us is that this was likely a pond that could have been conducive for newly hatched amphibians to develop in and for vegetation to grow that could have sustained the herbivores.”

Documenting localities like this helps capture environments that are known to have existed in the Permian, but are rarely encountered, he said.

And that is a “crucial part of building a more holistic picture of the environment and fauna at that time in North America,” he said.

Hidden secrets

Rosscoe said "it almost seems like a hidden secret of Taylor County" that there are some "amazing fossil deposits" here.

The recently-published Journal article focuses on vertebrate fossils, he said, the sort of thing one usually visualizes when thinking about dinosaurs.

But "while we don’t have any of those, our vertebrate fossils are really important additions to the overall Permian fossil record," Rosscoe said.

The specimens from this paper show that the fossil assemblage here in Taylor County is unique compared to others of similar age.

"This brings new information to our greater understanding of Permian paleontology," he said.

While not the focus of the paper, the Permian rocks in Taylor County also have a nice fossil assemblage of plants near the Buffalo Gap area.

"And we even have some nice amphibian footprints and other trace evidence of the life that lived here during that time," he said. "With every new study a more complete understanding of the overall Permian develops."

Of particular interest to Rosscoe is that the more recent finds were made by dedicated amateur paleontologists.

"Seeing folks so interested in science and geology brings real joy to my heart," he said.

And there's always room for more, he said.

"Hopefully, if they are really interested, I’ll even get a chance to see them in my classroom and maybe they’ll even become the next discoverer of something fantastic about geology in Abilene and Taylor County," Rosscoe said.

Source: www.reporternews.com