Sunday, July 1, 2018

Fossil Bison of the National Park Service

Last year for Fourth of July week I put up a post on dinosaurs of the National Park Service. With the same time of year upon us, I thought I'd try something similar. Now, we haven't had all that much change in NPS dinosaurs over the past year, but there's something else that's even more appropriate: bison. Cue the map!

For this map, parks with paleontological materials of bison are indicated, with two questionable occurrences (18 and 32) represented by gray question marks. See text for caveats. 1. Lava Beds National Monument; 2. Golden Gate National Recreation Area; 3. Santa Monica Mountains NRA; 4. Joshua Tree National Park; 5. Nez Perce National Historical Park; 6. Craters of the Moon National Monument & Preserve; 7. Yellowstone NP; 8. Fossil Butte NP; 9. Timpanogos Cave NM; 10. Arches NP; 11. Glen Canyon NRA; 12. Zion NP; 13. Tule Springs Fossil Beds NM; 14. Lake Mead NRA; 15. Grand Canyon NP; 16. Great Sand Dunes NP & Preserve; 17. Chaco Culture NHP; 18. Gila Cliff Dwellings NM; 19. White Sands NM; 20. Bering Land Bridge National Preserve; 21. Yukon-Charley Rivers National Preserve; 22. Denali NP & Preserve; 23. Theodore Roosevelt NP; 24. Wind Cave NP; 25. Badlands NP; 26. Missouri National Recreational River; 27. Tallgrass Prairie National Preserve; 28. Lake Meredith NRA and possibly Alibates Flint Quarries NM; 29. Waco Mammoth NM; 30. Padre Island National Seashore; 31. Ice Age National Scientific Reserve (affiliated); 32. Valley Forge NHP.

For bison, I'm not quite as confident with my records as I am for, say, mammoths or sloths or dinosaurs. In large part this is because bison are relative latecomers to North America and their record goes to the present. If you've got a random mammoth bone, nobody's going to blink an eye if you call it "Pleistocene", but a random bison bone is not so indicative. There are probably isolated occurrences of fossil material that I don't know about because they've been classified as recent or not classified at all. In addition, some researchers are strict about not considering specimens paleontological if they are more recent than a certain age, whereas I am not so strict about the Holocene. (Of course, then you get into the overlap with archeology.) Therefore, the list I have is subject to change. At this time, perhaps the most notable occurrence from these 32 parks is an early Holocene bison bonebed found in the Wisconsin side of Interstate State Park, one of the units of affiliated Ice Age National Scientific Reserve (I plan to cover it in more detail at another time). Otherwise, the record of NPS fossil bison is mostly isolated, incomplete material, with some bison dung in cave settings.

Distribution is dominated by parks west of the Mississippi, particularly those larger than a few hundred acres. There are some not currently listed, such as Big Bend NP, Death Valley NP, and Glacier NP, that would not surprise me if they eventually are added. East of the Mississippi we don't have as many large parks, and there's a definite tendency for large mammal records to come from caves, so I would expect to add some of the parks with caves over time.

Or maybe I should look at some of the coastal parks. From O. P. Hay's 1923 catalog of eastern North American Pleistocene finds (extant B. bison gets the next map in the volume).

One of the things you will encounter with the genus Bison in North America is the usual complicated taxonomy. The exact timing of the arrival of Bison in North America is not certain, but bison were established by at least 160,000 years ago. Bison arrived as Bison priscus, the widespread Steppe bison, which was not unlike the modern bison. B. priscus evolved into B. latifrons, which can be distinguished by its large size and enormous horns, and B. antiquus, which was not quite so large nor extravagantly equipped with horns.

For B. latifrons, there was never such a thing as having too much horn. Cincinnati Museum of Natural History & Science mount, photo by James St. John via Wikimedia Commons.

B. latifrons went out of the picture during the most recent Ice Age (a unique sense of timing compared to all of the species that went extinct right after), but B. antiquus was still there to carry the bison banner. B. antiquus in turn evolved into the yet smaller B. bison in the early Holocene, about 10,000 years ago. The transitional phase is sometimes described as another species (or subspecies), B. occidentalis. We ran into B. occidentalis way back in early 2014 on I-35E, and this is also the form that has been identified at the Interstate State Park bonebed.

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