Sunday, March 12, 2017

Xingxiulong

Two dinosaurs were published on February 16, 2017. One of them was Isaberrysaura mollensis, which has gotten a lot of press because it's a weird basal ornithischian with gut contents. The other was Xingxiulong chengi, which hasn't gotten as much attention, although the Wikipedia article is pretty extensive. Xingxiulong is among what we used to call "prosauropods", now known as basal sauropodomorphs. It is represented by most of the skeleton, excepting the tips of the jaws, most of the hands, and the coracoids and sternal elements. It also provides me a half-point on my prediction for "prosauropods", which I'll take because it's been kind of a slow year so far.

Sunday, March 5, 2017

Joseph Nicollet

Judging by place names, Joseph Nicollet must have been a much more popular man than George William Featherstonhaugh. (Or maybe it was just the fact that it took sixteen letters to spell George's name while only taking seven to say it that proved unappealing.) I'm not sure if anyone in Minnesota attached George's name to anything, whereas Nicollet is the namesake for such pieces of geography as Nicollet County, Nicollet Mall, and Nicollet Island. His name was even attached to a ballpark, the long-time home of the old Minneapolis Millers, although probably the adjacent Nicollet Avenue was the main inspiration.

Sunday, February 26, 2017

Subsurface paleontology of Lafayette Square and the Washington Monument

Washington, D.C. is not generally ranked in the first order of fossiliferous areas. It can hardly be considered a bust, though. The "Middle" Cretaceous Potomac Group (due to a tragic geologic oversight, there is no formal Middle Cretaceous) has been reasonably kind for plants; see Fontaine (1889, 1896), Knowlton (1889), Ward (1895), Ward et al. (1905), and Sinnott and Bartlett (1916) for some of the gory details. Something you may notice from that list is that all of those publications are at least a century old. The obvious problem is that Washington is a city first and foremost, so it's not like there are a lot of outcrops for prospecting any more. The Potomac Group has also produced some scrappy dinosaur remains, and anywhere that the Potomac River once flowed is liable to have cobbles with Skolithos tubes, eroded from Cambrian rocks up in the mountains. The classic Potomac Skolithos cobbles are rounded pieces of orangeish quartzite with simple vertical Skolithos burrows, similar to skinny pencils and with a tendency to stand out from the host rock. Washington is also blessed with a profusion of fossiliferous building stone, particularly the inevitable "Indiana Limestone" (Salem Limestone). But I digress. In a city, we cannot come to the outcrop, so the outcrop must come to us. This is where subsurface explorations come in handy. We talked about taking cores from lake sediments a few weeks ago. The subsurface of Washington, like any major city, has been picked at innumerable times, uncovering fossils from places such as just north of the White House and near the Washington Monument.

Sunday, February 19, 2017

Isaberrysaura, and the further revenge of gut contents

This week saw the publication of two new dinosaurs. Both of them have something to recommend them, but given my own preoccupations we'll have to leave Xingxiulong for someone else, or for another time. (Feel free to hop over to the paper, though!) Instead, we shall meet Isaberrysaura mollensis, a basal ornithischian packing an identity crisis and a belly full of seeds.

Saturday, February 11, 2017

George William Featherstonhaugh

I've been looking at some of the early geological expeditions in the United States for work, and I thought I'd take a couple of posts to look at some of the pre-Civil War geologists who visited the Twin Cities area of Minnesota. We've already briefly looked at William Keating and the Stephen Long expedition of 1823, so I thought I'd move on to the next figure of note, George William Featherstonhaugh.

George William Featherstonhaugh, borrowed from Wikimedia Commons, who borrowed it from the Minnesota Historical Society.

Sunday, January 29, 2017

Kirchner Marsh and the use of lake sediments

As we've seen from time to time with packrat middens, there are many ways of looking at past ecological conditions. A common method in more humid environments that the deserts and mountains of the Southwest is studying lake deposits, which is quite well-suited to the Land of 10,000 Lakes. Many types of paleoecologically useful fossils can be extracted from lake sediments, ranging from diatoms ("algae" with silica cell walls), to spores and pollen, to mollusks, to ostracodes, to the jaw parts of certain midge larvae. (There are, of course, other kinds of fossils that can be found in lakes, but they aren't as commonly used for paleoecological work. A single mammoth, while certainly of great interest, is not as versatile for this kind of thing as innumerable pollen grains spread over thousands of years.) Spores and pollen are part of a group of fossils known as palynomorphs, organic-walled microfossils. There are several other types of palynomorphs, including various cysts and so forth, but for the purposes of upper Pleistocene and Holocene lake sediments in Minnesota, spores and pollen are clearly the stars of the show.

Sunday, January 22, 2017

Mammoth roundup

A couple of new publications concerning mammoths in National Park Service units have crossed my desk recently, so it seemed like a good opportunity to say a few further words on behalf of extinct proboscideans in the National Parks. I present to you first the finely wrought map below, which shows the various parks where body fossils of mammoths, mastodons, and their friends have been reported. At press time, there were 37 parks, monuments, and so forth with confirmed records, and another six with possible records (cases where the locality is not clear). This map has the novelty of differently colored and shaped symbols, which aside from providing a splash of color, show a preponderance of mastodons in the northeast and mammoths in the southwest. I've relied on the literature and such, so there's definitely the chance that some of the "mammoths" are mastodons, and vice-versa. Most of these records are from the Pleistocene, but there are a few that are older; notably, John Day Fossil Beds National Monument and Niobrara National Scenic River have both gomphotheres and mastodons of pre-Pleistocene age. The great majority of the mammoth reports in the lower 48 are likely Columbian mammoths, Mammuthus columbi (M. exilis of Channel Islands National Park being a notable exception), but given the ambiguities in North American mammoth taxonomy, I figured it wasn't worth the time to try to split them up.

I use the base map a lot, don't I? Definitely a "click to embiggen" this time, to enjoy the various colored symbols. Inventory of points: 1) Nez Perce National Historical Park, multiple states; 2) John Day Fossil Beds National Monument, Oregon; 3) Hagerman Fossil Beds National Monument, Idaho; 4) Lava Beds National Monument, California; 5) Golden Gate National Recreation Area, California; 6) Death Valley National Park, California–Nevada; 7) Tule Springs Fossil Beds National Monument, Nevada; 8) Lake Mead National Recreation Area, Arizona–Nevada; 9) Mojave National Preserve, California; 10) Channel Islands National Park, California; 11) Santa Monica Mountains National Recreation Area, California; 12) Joshua Tree National Park, California; 13) Noatak National Preserve, Alaska; 14) Kobuk Valley National Park, Alaska; 15) Bering Land Bridge National Preserve, Alaska; 16) Denali National Park and Preserve, Alaska; 17) Yukon-Charley Rivers National Preserve; 18) Arches National Park, Utah; 19) Glen Canyon National Recreation Area, Arizona–Utah; 20) Grand Canyon National Park, Arizona; 21) Wupatki National Monument, Arizona; 22) Colorado National Monument, Colorado; 23) Florissant Fossil Beds National Monument, Colorado; 24) Great Sand Dunes National Park and Preserve, Colorado; 25) Bent's Old Fort National Historic Site, Colorado; 26) Salinas Pueblo Missions National Monument, New Mexico; 27) White Sands National Monument, New Mexico; 28) Lake Meredith National Recreation Area, Texas; 29) Big Bend National Park, Texas; 30) Amistad National Recreation Area, Texas; 31) Waco Mammoth National Monument, Texas; 32) Padre Island National Seashore, Texas; 33) Big Thicket National Preserve, Texas; 34) Buffalo National River, Arkansas; 35) Vicksburg National Military Park, Louisiana–Mississippi; 36) Niobrara National Scenic River, Nebraska; 37) Mississippi National River and Recreation Area, Minnesota; 38) Mammoth Cave National Park, Kentucky; 39) Potomac Heritage National Scenic Trail, multiple states; 40) Valley Forge National Historical Park, Pennsylvania; 41) New Jersey Pinelands National Reserve (affiliated), New Jersey; 42) Fort McHenry National Monument and Historic Shrine, Maryland; 43) Colonial National Historical Park, Virginia.