__________The Paleontograph________ A newsletter for those interested in all aspects of Paleontology Volume 4 Issue 4 October, 2015 _________________________________________________________________ From Your Editor Welcome to our latest issue. This issue is one of the final things I do before shutting down my office for my move west. With all that is going on, I've only managed 4 issues so far this year. My field season has suffered also although I did manage a few days of collecting dinosaur material in SD thanks to a friend that brought me along on one of his trips. I met a bunch of nice people and had a good time playing in the dirt for a few days. I set my booth up at the Denver Coliseum show again this year and had an extremely successful show. For those of you that don't go to shows, I recommend it even if you are not a buyer. There are always cool things to see and cool people to meet. I went to shows for years before I started my business because I was always fascinated by what the commercial market brings to light that the scientific community just misses due to lack of funding, time, storage and just plain lack of interest. The shame of it is that as many in that community try to shut down the fossil marketplace, there are fossils out there just eroding away into dust. Anyone that spends time in the field as opposed to time at a desk can attest to this. The desk people also don't realize the chilling effect this will have on the pursuit of knowledge. Commercial and amateurs are responsible for many great finds as well as small finds that help round out the picture of what ancient times were like. Once again, thanks to Bob Sheridan for continuing to produce the quality writing you are about to read. I hope you enjoy this all Dinosaur edition. The Paleontograph was created in 2012 to continue what was originally the newsletter of The New Jersey Paleontological Society. The Paleontograph publishes articles, book reviews, personal accounts, and anything else that relates to Paleontology and fossils. Feel free to submit both technical and non-technical work. We try to appeal to a wide range of people interested in fossils. Articles about localities, specific types of fossils, fossil preparation, shows or events, museum displays, field trips, websites are all welcome. This newsletter is meant to be one by and for the readers. Issues will come out when there is enough content to fill an issue. I encourage all to submit contributions. It will be interesting, informative and fun to read. It can become whatever the readers and contributors want it to be, so it will be a work in progress. TC, January 2012 Edited by Tom Caggiano and distributed at no charge [email protected] PALEONTOGRAPH Volume 4 Issue 4 October 2015 Page 2 Brontosaurus Resurrected? partially incomplete, and some are very fragmentary, e.g. are isolated skulls or femurs, so not every character can be coded for every specimen. Bob Sheridan, April 11, 2015 However, computational methods handle this type of situation very well. There is an interesting chart in Sauropods are very large dinosaurs with long tails this paper showing which specimens can be coded and long necks. They come in a number of families, for which characteristics. It should be noted that not most of which lived in the Late Jurassic, although every study of this type is at the level of individual some survived to the Cretaceous. The specific family specimens. Most use genera as the unit. The we are talking about today are the Diplodocidae advantage of using individual specimens is that one ("double beams"). Diplodocids generally have can see whether the assignments of species and longish necks, whip-ended tails, and shortish legs. genera is self-consistent according to anatomical They also have long heads with nostrils at the top of features. the skull and peg-like teeth. The group contains some very well known genera such as Diplodocus The aim of such studies is to produce cladograms or (for which the group is named), Apatosaurus, and "trees" that shows which "taxonomical units" Barosaurus, as well as some obscure ones such as (specimens, genera, etc.) are related to which others Galeomopus and Leinkupal. Most diplodocids are and how closely. The cladograms are sensitive to excavated from the Morrison Formation of North adjustable parameters and assumptions, so a America. prudent investigator produces cladograms several ways to see which conclusions will hold up. One As with any type of dinosaur, the assignments of result of the Tschopp et al. study seems robust: the specimens to genera is always in flux. For example, two specimens originally named "Brontosaurus" "Supersaurus" and "Seismosaurus", once their own cluster together, and seem similar to specimens genera, were later assigned to Diplodocus. The named "Eubrontosaurus" and "Elosaurus". This oldest and most famous reassignment is group forms a sister group to three specimens "Brontosaurus." The great nineteenth century named "Apatosaurus," plus two other specimens not paleontologist O.C. Marsh described Apatosaurus yet assigned a genus. The differences between ajax in 1877, and then gave a different name "Brontosaurus" and "Apatosaurus" could be enough "Brontosaurus" to a separate specimen of a very to say they are different genera. Most of the similar dinosaur two years later. He also mistakenly distinction comes from the anatomical detail of the assigned to Brontosaurus the skull of neck vertebrae. Camarasaurus, an unrelated sauropod. Elmer Riggs, in reviewing the literature on sauropods known up to 1903, thought Brontosaurus was not The popular press has seized upon this finding with sufficiently different from Apatosaurus to deserve its headlines about "Brontosaurus" returning. I am own genus, and the older name took precedence. reminded of when, a couple of years ago, we heard By that time, however, the blunt-skulled, tail- that Archaeopteryx was "knocked off its perch" as dragging, semi-aquatic image of "Brontosaurus" was the first bird, because it nested with dinosaurs an icon of popular culture. It was not until the 1970's instead of birds when Anchiornis was added to a that Apatosaurus was finally assigned the correct cladistic study, but not when Anchiornis was left out. long Diplodocus-like skull. AMNH didn't revise its There is some hype involved with such headlines. "Brontosaurus" mount until the refurbishment of the You should keep the following in mind: Dinosaur Halls in the mid-1990's. 1. Such findings need to be repeated and checked against new specimens. Although, It is quite common for paleontologists to reanalyze this is probably the best study so far, groups of dinosaurs to take into account new remember that we are dealing with specimens, with more powerful computational incomplete information and mathematical techniques for generating cladograms, using ever- methods that are never perfectly precise. more specimens and more characters. The new Since the sample sizes are so small, it may not be work by Tschopp (2015) is an example of such a possible to truly know whether animals are truly study. These authors included 81 individual distinct as genera or species or are just along a specimens of sauropod, of which 49 are diplodocids. continuum. Also it is always possible mistake They noted 477 individual anatomical characters animals of different ages or sexes as different using all parts of the skeleton. It should be pointed genera. out, of course, that all specimens are at least Cont'd PALEONTOGRAPH Volume 4 Issue 4 October 2015 Page 3 Brontosaurus Cont'd Ontogeny of Centrosaurus 3. It is not clear that "Brontosaurus" will ever be revived as a valid genus name. It may be decided that all these specimens should keep Bob Sheridan, April 19, 2015 the name "Apatosaurus", but the species names need rearranging. The pre-1970s blunt- Ontogeny is the anatomical trajectory an animal skulled, tail-dragging, iconic "Brontosaurus" will takes as it ages. For a fossil animal, it is important to never come back since it is a mistake. know something about its ontogeny because there is always the danger of confusing animals of different ages (or sexes) as different genera or species. This is especially an issue with dinosaurs. For example, the issue of whether Nanotyrannus is a juvenile Tyrannosaurus or a separate dwarf species is still open, after 30 years of debate. More recently we have the debate over whether Torosaurus is really just a very old Triceratops. Generally speaking, unless there is a complete "growth series," where one can see various intermediate steps in an animal growing, which differences are ontological and which differences represent different species will never be so obvious that such debates can be avoided. Off the top of my head, I can think of only one dinosaur species Protoceratops andrewsi for which we have anything like a complete growth series. Nowadays, it is a common practice to estimate the age of a dinosaur specimen by sectioning its long Finally, a side comment. When I first saw mention of bones. Most dinosaurs have concentric "lines of the Tschopp et al. study in Science yesterday, I arrested growth" (LAGs), which indicate a time hadn't heard of the journal PeerJ in which the study where the growth of the animal slowed. Assuming appears. PeerJ is an open-access journal that has one LAG per year, one can read the age of the been around a few years, and I found at least three animal by counting LAGs in the bones, much as we articles on paleontology. Anyone with an internet estimate the age of a tree by counting rings.