Eocene Land Mammals

[Harry Pristis]

I live in Florida, the place of abundant Neogene (Miocene, Pliocene, Pleistocene) mammal fossils. We just don't have much in the way of Paleogene (Oligocene, Eocene, Paleocene) land mammal fossils in the Southeastern U.S. I hadn't given Paleogene fossils much attention beyond a handful of fossils from the Badlands in Northcentral states. That is, until I acquired some examples of Late Eocene perissodactyls from Europe. Here's what I discovered:

Plagiolophus (and sister taxa) are palaeotheres, a successful and variable family of perissodactyls (horses, rhinos, tapirs, et. al.) in the Eocene of Western Europe. Not true horses, palaeotheres may be the ancestors of horses. Plagiolophus represents one genus of palaeothere, extinct since the Oligocene. Plagiolophus minor, a browser, was the only member of its family to survive more than fleetingly the mammalian faunal turnover, the "Grande Coupure," which occurred during the earliest Oligocene in Europe.

La Debruge is one of about 15 terrestrial faunas (fossil remains of all kinds: plants, aquatic and terrestrial invertebrates, microfossils, vertebrates, mammal footprints) in the Apt-Forcalquier-Manosque basin in the French Alps. (Apt is a small town and is an administrative center of the Vaucluse district.) It is a mostly-paleogene basin with no outflow that accumulated siliciclastic alluvial sediments along with carlcareous deposits in fluctuating shallow lakes.

The Paleogene of the basin starts in the Late Eocene with a coastal plain to supratidal flat environment temporarily covered by salt lakes or flood plains and progresses further to a truly closed lacustrine drainage basin towards the Early Oligocene. The Oligocene broadly saw the development of a fluctuating fluvial/lake-system with calcareous, clay and siliciclastic deposits.

Many mammals and other vertebrate fossil remains are known from this period all over the region. The Neogene (Miocene) saw a return to marine conditions with the Burdigalian transgression, leaving large thicknesses of sediments from erosion of the rising Alp Mountains.

The Late Eocene of the basin is known worldwide for the "La Débruge" mammal fauna serving as a reference locality to the European biochronological timescale. The La Debruge reference level zone is Priabonian (37.2 - 33.9 Ma). The La Débruge fauna slightly precedes the Grande Coupure event which saw a renewal of worldwide faunas at the Eocene-Oligocene boundary.

The very abundant fossils of the La Débruge fauna were found in an organic-rich deposit indicating a pond-like environment. The sediments are blackish and slightly sandy marls. Contrary to an earlier report, the fossiliferous level contains no lignite. The fossiliferous layer is about 50 cm (~20 inches) thick.

Since 1987, the basin has been protected as the Parc Naturel du Luberon.

For more info on the Grande Coupure see http://en.wikipedia.org/wiki/Eocene%E2%80%93Oligocene_extinction_event

Who here has some Eocene land mammal fossils from anywhere to show us!?

[jpc]

Very nice, Harry. I would love to get my grubby paws on French Eocene mammals. It is not easy these days, esp since I am primarily a self collecting kinda guy.

[caterpillar]

You can see some eocene mammals of France there:

http://lithotheque.franceserv.com/vertebres/fiche_etage.php?etage=Priabonien

http://lithotheque.franceserv.com/vertebres/fiche_etage.php?etage=Lutetien

http://lithotheque.franceserv.com/vertebres/fiche_etage.php?etage=Ypresien

[MarcoSr]

Who here has some Eocene land mammal fossils from anywhere to show us!?

Eocene land mammal fossils are very rare from Virginia. I am aware of 15 specimens only from the Ypresian, Nanjemoy Formation of Virginia from a site which was near shore marine. Most of the specimens are isolated teeth or tooth fragments but several, small mammal, partial jaws have also been reported. Below is a 7mm partial marsupial jaw from the Eocene of Virginia that I donated to the Smithsonian years back.

Marco Sr.

[Harry Pristis]

Thanks for the responses, guys. Caterpillar has an extensive web-collection of Eocene mammal fossils. And, how rare is that marsupial which MarcoSr found!

I realized I had a few Eocene fossils to which I had given no attention for more than 20 years.

Here's one of 'em:

Edited October 22, 2014 by Harry Pristis

[caterpillar]

Very nice Harry. Adapis is not the must common

[jpevahouse]

A few Brontothere bones from the Western US Eocene. Upper molar, distal (lower) end of humerus (lower front leg bone) and upper section of juvenile femur (upper rear leg bone). Brontothere, a rhinoceras like animal, were the largest animals of the North American Eocene reaching almost the size of an elephant at their maximum size. They survived through the early or middle Oligocene era.

Edited October 22, 2014 by jpevahouse

[MarcoSr]

And, how rare is that marsupial which MarcoSr found!

The jaw was described and named "Peradectes gulottai new species" by Dr. Kenneth D. Rose in a 2010 paper.

Marco Sr.

[PFOOLEY]

The jaw was described and named "Peradectes gulottai new species" by Dr. Kenneth D. Rose in a 2010 paper.

Marco Sr.

How cool is that?! Congratulations on the name.

[herve]

Hello J have some mammals from la Debruge. J have find in 1985 now its impossible for find its forbiden,parc du luberon Best regards

[MarcoSr]

How cool is that?! Congratulations on the name.

Mike

Thanks, I was really happy when I found someone just willing to describe the specimen. It is much better that the specimen is described and in a museum collection versus being in a gem jar display in one of my fossil drawers. I'm still trying to get 70+ bird bones from the same site looked at.

Marco Sr.

[Harry Pristis]

^{Herve . . . Post some images of your mammal fossils. Or, you can send them to me so I can photograph them}

Here is another Eocene fossil that I found in my drawer:

Didymictis is a creodont. The Creodonta are an extinct order of carnivorus mammals which were important in North America, Africa, and Eurasia from the Late Eocene to Middle Oligocene (55 Ma.- 35 Ma.). Creodonts were probably out-competed by the other important order of meat-eaters, the Carnivora. The last genus of creodonts went extinct in the Miocene of Africa.

[Harry Pristis]

_{This line-drawing wouldn't fit into the preceding post:}

[jpc]

I just spent two days in the Eocene of Wyoming looking for mammals... found a few jaws and teeth and two partial skeletons. Partial skeletons is a bit of an exaggeration... how about collections of post-cranials. I will try to post photos later.

[Harry Pristis]

I just spent two days in the Eocene of Wyoming looking for mammals... found a few jaws and teeth and two partial skeletons. Partial skeletons is a bit of an exaggeration... how about collections of post-cranials. I will try to post photos later.

That's great, jpc! I never got into Wyoming to collect when I was hunting the Mauvaises Terres of Western Nebraska and S.D. My regret. We'll be eager to see images of your finds.

[siteseer]

Great topic, Harry.

I have some Eocene mammals and have been meaning to get some photos taken. I have bought or traded for them whenever I could. I still have some unidentifed specimens as well. As you know, you see flats and flats of North American Oligocene mammals at the bigger shows but maybe only a small box or two of Eocene mammals (if that). The sites seem to be fewer in number, though when you read up on them, a lot of long-known sites don't seem to get collected any longer (perhaps BLM or park land now). It may also be that these sites are not as productive. You can spend all day looking and end up with only a handful of stuff. Still, if you find some decent teeth, it might be worth it to someone interested in keeping a sample of a wide range of mammals.

The Early Eocene, the warmest interval of the Cenozoic Era (almost unbroken subtropical jungle from New Mexico to the Arctic Circle), was a time when the earliest horse, tapir, and titanothere would have resembled each other and were about the same size. Rodents were uncommon and just starting to appear in North America. The ancestors of modern carnivorans were small weasel-like forms and the largest herbivorous mammal, Coryphodon, (a mammal belonging to a group that died out by the end of the Eocene) was the size of a cow. Hyopsodus, a herbivore belonging to a now-extinct group, was common. The oddest mixture of mammals of all time lived during the Eocene: some survivors from the Cretaceous (multituberculates); some from the Paleocene (creodonts, Plesiadapis, pantodonts like Coryphodon, etc.) and various early representatives of modern orders. Some of the teeth you see are very unusual relative to Miocene-Pleistocene mammal teeth.

For some reason, when you see some Eocene land mammal fossils from North America, they tend to be Early Eocene age. I've seen only a few Middle Eocene specimens (Orohippus, Notharctus, early tapir) and no Late Eocene ones.

Jess

[Harry Pristis]

Jess . . . I'm sure you have some excellent North American specimens. Please post some images!

[jpc]

As a frequenter of Wyoming's Eocene, I can add this to Jess' comments. But first I'll add that I am old enough that the base of the White River Fm was early Oligocene when I started all this, and now it is latest Eocene, but the stuff I am talking about is early Eocene. Wyoming is well known for its early and mid Eocene fossils, esp the Green River fish and mammals from a variety of formations. many paleontologists spend their summers out here collecting Eocene mammals. But.... There is a reason they come here for large chunks of the summer. These things are not common. You can walk about on Eocene sediment out here and find lots of turtle pieces, and occasional crocodile bits, but mammals are not guaranteed. My above reply tells you how many jaws you might find. The two partial skeletons I found are actually pretty darn special... I have only found two previous partial Eocene mammal skeletons in more than 15 years of searching. Most of the land where you find them is on BLM land, so off limits to most of us. This is why you rarely see them at the usual rock shows. They are labor intensive and hard to find. And just not as spectacular as the White River material.

And I know that a lot of the French sites are off limits to collectors as well.

Edited October 27, 2014 by jpc

[siteseer]

Thanks, JP.

Yes, the one time I was able to prospect the Eocene was near Opal, WY. A landowner allowed a friend and I to look around. As you said, all we found were pieces of turtle shell and miscellaneous bone bits.

Among all the Eocene teeth and jaw sections from Wyoming (just a few from New Mexico too) I have seen, there are very few postcranials. I have about half a toe bone but only because it's stuck to a jaw section.

The other reason you don't see a lot of it at shows is that it there isn't a lot of collector interest. It's like you said. It's unspectacular from a size standpoint except for the brontothere and uintathere stuff. Mammal collectors like to have a Hyracotherium jaw section because it's the earliest horse and you can make a display of 8-9 fossil horse genera without too much difficulty but not many try to build a collection of Eocene forms. Also, because many of the forms belong to groups that died out even before the Oligocene, there isn't much familiarity and there is no ID guide out there to help. One of my friends (the Fossil Forum's own fossillarry) is very knowledgeable about mammals with expertise in Eocene forms. I know one French dealer who is also very knowledgeable about Eocene mammals and he hunts a site near where he lives. Another dealer, Geert Nijboer, was very good too but he passed away early last year. Outside of those guys it's tough to find people to talk about this stuff - not just for ID but just to talk about it in general.

Jess

As a frequenter of Wyoming's Eocene, I can add this to Jess' comments. But first I'll add that I am old enough that the base of the White River Fm was early Oligocene when I started all this, and now it is latest Eocene, but the stuff I am talking about is early Eocene. Wyoming is well known for its early and mid Eocene fossils, esp the Green River fish and mammals from a variety of formations. many paleontologists spend their summers out here collecting Eocene mammals. But.... There is a reason they come here for large chunks of the summer. These things are not common. You can walk about on Eocene sediment out here and find lots of turtle pieces, and occasional crocodile bits, but mammals are not guaranteed. My above reply tells you how many jaws you might find. The two partial skeletons I found are actually pretty darn special... I have only found two previous partial Eocene mammal skeletons in more than 15 years of searching. Most of the land where you find them is on BLM land, so off limits to most of us. This is why you rarely see them at the usual rock shows. They are labor intensive and hard to find. And just not as spectacular as the White River material.

And I know that a lot of the French sites are off limits to collectors as well.

[Harry Pristis]

Base on jpc's remarks about the White River Formation, is it appropriate to change the label on this fossil from Oligocene to:

Family BRONTOTHERIIDAE
Megacerops sp. LEIDY, 1870

Late Eocene

White River Formation

Pennington County, SD

[siteseer]

Harry,

Yes, I would do that. Brontotheres became extinct in North America at the end of the Chadronian which used to be considered Early Oligocene. Now, it's within the Late Eocene. Brontotheres survived into the Early Oligocene in Asia.

I wasn't thinking about the Chadron beds when I said I hadn't seen any Late Eocene mammal fossils from North America. A friend used to dig for that in Wyoming (and Nebraska too, I believe).

Jess

Base on jpc's remarks about the White River Formation, is it appropriate to change the label on this fossil from Oligocene to:

Family BRONTOTHERIIDAE
Megacerops sp. LEIDY, 1870

Late Eocene

White River Formation

Pennington County, SD

brontothereM2.JPG

[Harry Pristis]

Okay, fellas, I think I see what I need to say on the label. Thanks.

[jpc]

Change in label approved

[Harry Pristis]

I did a bit of reading about the provenance of the little French lemuriform primate, Adapis parisiensis. Remember?

Here's what I found:

"Phosphorite" is a phosphate mineral which is found as microcrystalline concretions of continental (non-marine) origin.

Quercy is the name of a 18th century province in the southwest of France. The region of Quercy is notable for its limestone plateau and valleys -- a karstic geology.

Phosphorite was mined for fertilizer in Quercy from filled karst cavities -- sinkholes and solution channels -- within a hard, Jurassic limestone. These pockets of phosphate were mined between 1870 and 1890 and then abandoned.

Some early reports were done on the fossils from these phosphate pits. Intensive paleontological work was undertaken in 1965.

Terrestrial fossils from the phosphate diggings include many individual faunules from Eocene to Miocene in age. Mammals, reptiles, amphibians, and even insects have been collected.

The Natural Park of the Quercy, established in 1999, covers 175,717 hectares (678 square miles) and includes 97 municipalities. The park includes three geological environments: the plateau, the valleys and

Limargue (another natural region) to the east, with a network of rivers.

[caterpillar]

Right Harry. The Park is one hour to my home