Terminology and Expectations
Type specimen is the specific specimen upon which the description of a new species is initially based. It is usually chosen by the person naming a new species as “the standard of reference to represent his or her concept of that species.” (Donald R. Prothero, Bringing Fossils to Life: An Introduction of Paleobiology, p. 59.)
Given the importance of these specimens, Prothero also observes:
Normally, type specimens are deposited in a major museum or other reference collection with scientific access, so other scientists can examine them. (p. 60, emphasis added)
Then, again, this expectation may not be realized because a type specimen may not end up in a museum or any collection at all. It may have to stay where the person doing the naming found it, wherever that might be. And that wherever may drastically change who has access to it.
In the early 1930s, a slab of limestone containing a dramatically well-defined, three-toed dinosaur track was cut out of the bed of the Paluxy River, at the so-called “fourth crossing” of the river, a spot some six miles west of the Texas town of Glen Rose. This piece of Cretaceous period limestone, replete with dinosaur track, was then incorporated into the wall at the base of the town’s bandstand in front of the Somervell County Court House, where it remains.
In 1934, a year after it became part of the bandstand, geologist Ellis W. Shuler from Southern Methodist University visited the dinosaur track. He returned a year later with a small team to examine the track more closely. Measurements were taken (25 inches from heel to end of the middle toe, and 17 inches across the toes) as was a cast. Shuler shot the picture below.
Presumably based on, among other details, the features of the foot revealed by the track and the overall length of the stride (the track was one of a series of four in the riverbed), he concluded:
The individual dinosaur making the track was most certainly of the flesh eating type, catching its prey by high bursts of speed. The name Eubrontes (?) glenrosensis sp. nov. is suggested for this species.
~ “Dinosaur Track Mounted in the Band Stand at Glen Rose, Texas,” by Ellis. W. Shuler, Field and Laboratory, Volume 4, Number 1, November, 1935, p. 13
In one fell swoop, Shuler both gave a name to this ichnofossil (trace fossil) and took it back, well, at least, partially. (He was naming the trace fossil, not the animal that actually made the track.) The question mark following Eubrontes denotes doubt that this ichnofossil belongs to the Eubrontes ichnogenus. And, apparently, there remains some doubt among paleontologists today.
As I wrote this out, I realized there has been a recurrent feature in this blog -- small biographical portraits of the people who do science, particularly paleontology.
I assume that Ellis Shuler, as one the first faculty members hired at Southern Methodist University in 1915, initially constituted the entire geology faculty at the institution. The Harvard-trained Shuler served at SMU for 35 years, retiring in 1952, the last of the original hires to retire.
The roots of his attraction to geology and paleontology lie in his childhood in Virginia. It’s a story recounted in the opening of his book, Rocks and Rivers (1945):
My first lesson in geology came in singular fashion. A boy of fourteen, I had just finished reading The Last Days of Pompeii when a series of earthquakes shook the little town of Pearisburg, Virginia, where my father preached.
This was probably in 1895. His father prevailed on the U.S. Geological Survey to send a geologist to look into the origins of the earthquake. Marius R. Campbell arrived and reassured the boy that a volcanic eruption was not imminent. Campbell then joined the Shuler family as they journeyed to a summer resort up near the top of Salt Pond Mountain. They trekked by foot along a road up the mountain. Recalled Shuler,
As I tramped barefooted by his side, Mr. Campbell discovered for me a new world in the shale beds by the roadway.
“These are fossils, sea shells,” he said.
With Campbell’s guidance, the boy filled his pockets with fossils, some quite rare.
The following day, boy and man stood at the top of the mountain. Campbell set up a camera to capture the vast landscape of river, valley, lake. Shuler asked, “Mr. Campbell, what makes mountains?” Campbell looked at the boy and said, “You are a funny kid.” And then proceeded with a lesson in geology.
I have to assume that Shuler intended Rocks and Rivers to be one of the crowning achievements to his career. It may well have been. An accessible, somewhat technical exploration of different key features of the natural geological landscape, the book clearly was a labor of love. Given the dry and fact-driven writing that he saw permeating professional writing in this science, Shuler set out to do something different. The book, he wrote, was “an adventure” and he hoped “that the romance and occasional levity in this volume may be pardoned.”
But, it has not aged well, I fear. When I first learned about Rocks and Rivers, I lost little time finding it in a used book store, hoping it would be an unheralded treasure. If only the tone, style, and intimacy of “A Personal Foreword” which opens the book (and is the source of the quotations above) marked the entire effort, any dated geological explanations would not have been sufficient to condemn the book to the out-of-print and unread world where it now resides. Among other limitations, without benefit of the theory of plate tectonics, it struggles for explanations of some landscape features. Still, I did like parts of the book besides the Foreword, including a chapter on glacier action shaping the landscape. A very solid treatment of that subject as far as I can tell. Alas, though, for me, those few, intimate, almost lyrical pages of the Foreword, which are the highlight of the book, promise much that isn’t delivered.
Buildings in a Small Town
What’s missing in Shuler’s picture above of the track inset in the bandstand wall is any hint of what surrounds the slab of limestone. The entire base of the bandstand has a facade of inlaid pieces of petrified wood.
Petrified wood turned up so frequently in local farmed fields that, beginning in the 1920s, it became a common decorative material for buildings in the Glen Rose area, being used in buildings ranging from homes to hotels, from restaurants to gas stations. The county courthouse behind the bandstand shares in that town custom. Indeed, this decor for buildings in Glen Rose is so common that the town, reportedly, is known as the “Petrified City.”
Back to the Wall
An outdoor bandstand is probably not the best place to keep a type specimen. After three-quarters of a century of exposure, this piece of Glen Rose limestone, laid down in the Cretaceous, is eroding. And with this erosion, details of this type specimen of Eubrontes (?) glenrosensis are fading.
But, still, for 75 years, this type specimen has been available for study by anyone, and I mean, anyone – tuba player or tuba lover or . . . .
I wonder whether other type specimens have been this accessible.
Postscript and Credits
In an effort to preserve as much detail of the fossil as possible in its present condition, SMU paleontologist Thomas L. Adams has used a portable scanner to create three dimensional digital models of this specimen. It was news coverage of his work that first interested me in Eubrontes (?) glenrosensis and Ellis Shuler. Photographs in this posting are by Ellis Shuler and Thomas L. Adams of SMU. They are reproduced by permission, and appear in the SMU Research blog in the 2009 article entitled Portable 3D laser technology preserves Texas dinosaur's rare footprint by Margaret Allen.
An interesting look at the town is provided in Glen Rose, Texas, by Gene Fowler and the Somervell County Historical Commission, a book in the Images of America series, 2002.
Dinosaur Valley State Park is near Glen Rose and abounds with dinosaur tracks. The site is managed by the state of Texas’ Parks and Wildlife Department. A brochure can be found here.
The Park is also a National Natural Landmark, participating voluntarily in this U.S. National Park Service program. A brochure about the Landmarks and the program can be found here.
Of interest (and a subject I chose not to get into) is On the Heels of Dinosaurs: An Informal History of the Texas "Man Track" Controversy by Glen J. Kuban. Link here.