Field of Science
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in The Biology Files
Abstract - The holotype specimen of the non-pterodactyloid pterosaur Eudimorpodon rosenfeldi from the Late Triassic of NE Italy is described in detail and compared to other specimens referred in the literature to the genus Eudimorphodon. It is considered conspecific with the specimen MPUM 6009 from the Norian of NW Italy, previously attributed to Eudimorphodon ranzii. A new genus, Carniadactylus, is proposed for the two specimens based on the apomorphic shape of the 'coranoid' process, coracoid and pteroid, wing phalanx proportions and the several anatomical differences with E. ranzii and 'Eudimorphodon' cromptonellus. No definitive evidence of a juvenile stage occurs in the two specimens. A phylogenetic analysis using parsimony shows that Carniadactylus is nested inside the Campylognathoididae and is the sister-group of Caviramus schesaplanensis + 'Raeticodacylus' filisurensis. The systematics of specimens referred in the literature to Eudimorphodon is reviewed.
Here is a picture of a large (six feet by three feet) block from a current excavation. We have now focused our attention on the trench around the specimen and isolated elements we are finding in the trench. Notice how nonchalant we have become regarding the previous center of our attention. It has now become a seat, a foot rest, a table for the iPod and speakers, and a place to put drinks, tools, etc...
Abstract - A jaw fragment with three teeth preserved, collected from the Gorno Formation (Carnian, Upper Triassic) of Lombardy (Italy) is described. The teeth are transversely elongated, three-cusped and bear anterior and posterior cingula. Their overall morphology supports their identification as postcanines of a gomphodont cynodont. The unique tooth morphology of the new specimen supports its attribution to a new genus and species, while at the same time precluding positive assignment to already known gomphodont families. There is a fairly small record of gomphodont cynodonts in Europe, so that the described specimen adds to the knowledge of the distribution and diversity of European gomphodonts and it also represents the first ever collected in Italy.
The authors acknowledge that these teeth are remarkably similar to those of pycnodont fishes; however, they argue strongly for synapsid affinities instead although they admit that the morphology is unique for that group. Indeed, the overall morphology of the teeth is extremely similar to that of pycnodonts (compare Figure 2a in Renesto and Lucas (2009) to a toothplate of Coelodus stantoni pictured here), but I am not familiar enough with synapsids or pycnodonts to make a determination either way. Even though the pycnodonts pictured at the Oceans of Kansas Site are from the Cretaceous, pycnodonts are known from the Late Triassic of the Tethyan Region (including Italy). Furthermore, the formation in which the specimen was recovered (the Gorno Formation) has been interpreted as lagoonal deposits and thus could support either interpretation.
The new taxon erected for these teeth is Gornogomphodon caffii.
The first fossils in this area were discovered by Annie Alexander (and her collecting partner Louise Kellogg) of the University of California at Berkeley in 1921. The two women were later accompanied by Charles L. Camp who excavated the fossils that they had discovered. Fortunately they had a camera along and photographed several of the sites. Thus we can recreate the shots. The historic photos are part of the PEFO collections, but are courtesy of the UCMP.
The photo below shows from left to right, Kellogg, Alexander, and the fossil preparator Eustace L. Furlong looking under a boulder at an exposed phytosaur skull (the holotype of Machaeroprosopus lithodendrorum). Photo is presumably by Charles Camp.
This is the exact same spot in 2009. Unfortunately some of the boulders have shifted (and Camp moved the one Kellogg was sitting on to get at the skull) so I could not achieve the exact angle (I am too low), but it is close enough. Furthermore camera lenses were different in 1921 from our modern digital cameras so that factors in as well when recreating shots. Notice how not much has changed in 88 years including the placement of even some of the smallest boulders.
The reknowned naturalist and author John Muir was not a full-time paleontologist but he was the first person to collect fossils in the Petrified Forest, and in fact it was his small collection that later spurred the more intensive work of Camp and Alexander. Muir spent much of 1905 and the beginning of 1906 at the small railroad stop of Adamana which at the time was the gateway to the Petrified Forest. Muir was there to write a series of articles on the Petrified Forest (never completed). His daughters Helen and Wanda were with him and a major reason they were in Arizona was to experience the dry desert air for Wanda's health. Muir and his daughters took numerous photographs of their visit and these are among the earliest known photos of Adamana and the park. A major set back for Muir during his time here was the death of his wife Louisa in early August, 1905 but he later returned to the area with his daughters. I have posted some of the photos below. These are courtesy of the National Park Service.
Photo of Muir's tent in the snow at Adamana in December of 1905. Note Muir's hand labelling of the photo.
Muir studying a petrified log.
Museums are places of learning and the curatorial position is an integral part of the learning process. Essentially the curator is a specialist who interacts with the public and the professional community promoting understanding of the resources under their care. Without this specialist interaction the museum exhibits are essentially nothing but curiosities and visitors will gain little regarding understanding and appreciation of these fossils and their significance. The university administration should realize that a part-time security guard cannot serve this purpose and eventually they will have to hire a specialist to run the museum. In the meantime their short-sightedness has cost the fine specialist they already had his job and cheated future visitors his knowledge and passion of the fossils of Wyoming.
Nice try UW, but again you have missed the point and as a result education and outreach suffers.
Here is what has been exposed so far. The entire rear left portion of the skull is very well preserved and the elements are freeing nicely from the sandstone matrix. Anterior (forward) is to the left. Abbreviations are as follows: f, frontal; ltf, lateral temporal fenestra; na, nasal; orb, orbit; po, postorbital; q, quadrate; qj, quadratojugal; and sq, squamosal.
We'll keep following as preparation continues. We are pretty excited about this skull as it appears to be relatively pristine.
Abstract- The phylogenetic relationships of Silesaurus opolensis have been the subject of intense debate since its discovery. Silesaurus possesses some features characteristic of ornithischian dinosaurs, such as the presence of a beak at the front of the lower jaw, yet it lacks a number of important femoral and dental synapomorphies of Dinosauria. The microstructure of the long bones (femur, tibia and metatarsal) and ribs of this species reveals a relatively intensive rate of growth, comparable with that seen in small dinosaurs and the gracile crocodylomorph Terrestrisuchus. Cortical bone formed mainly by periosteal tissue with fibro-lamellar matrix (in older specimens parallel fibred) shows very little secondary remodelling and only in one specimen (large tibia ZPAL Ab III ⁄ 1885) few lines of arrested growth are present in the outermost cortex. The vascularization is relatively dense, mainly longitudinal and ceases towards the periphery, forming almost avascular parallel fibred bone at the bone surface. This indicates maturation and significant decrease in the growth ratio in mature specimens of S. opolensis. The delicate trabeculae exhibit cores formed by the primary cancellous tissue lined with lamellar endosteal bone. The rather intense growth of S. opolensis implies a relatively high metabolic rate. Moreover, evidence from the fibro-lamellar tissue, predominant in the cortex, suggests that this kind of rapid bone deposition could be more typical of Archosauria than previously assumed, a prerequisite for the evolution of the very fast growth rates observed in large ornithischians, sauropods and large theropods.
Zanno, L.E, Gillette, D.D., Albright, L.B., and A.L. Titus. 2009. A new North American therizinosaurid and the role of herbivory in ‘predatory’ dinosaur evolution.Proceedings of the Royal Society B. Published online before print July 15, 2009, doi: 10.1098/rspb.2009.1029
Historically, ecomorphological inferences regarding theropod (i.e. ‘predatory’) dinosaurs were guided by an assumption that they were singularly hypercarnivorous. A recent plethora of maniraptoran discoveries has produced evidence challenging this notion. Here, we report on a new species of maniraptoran theropod, Nothronychus graffami sp. nov. Relative completeness of this specimen permits a phylogenetic reassessment of Therizinosauria—the theropod clade exhibiting the most substantial anatomical evidence of herbivory. In the most comprehensive phylogenetic study of the clade conducted to date, we recover Therizinosauria as the basalmost maniraptoran lineage. Using concentrated changes tests, we present evidence for correlated character evolution among herbivorous and hypercarnivorous taxa and propose ecomorphological indicators for future interpretations of diet among maniraptoran clades. Maximum parsimony optimizations of character evolution within our study indicate an ancestral origin for dietary plasticity and facultative herbivory (omnivory) within the clade. These findings suggest that hypercarnivory in paravian dinosaurs is a secondarily derived dietary specialization and provide a potential mechanism for the invasion of novel morpho- and ecospace early in coelurosaurian evolution—the loss of obligate carnivory and origin of dietary opportunism.
The therizinosaur skeleton was difficult to prepare due to the matrix and diagenetic crushing of the elements, but at the time it was collected it represented the first evidence of therizinosaurs from North America. Doug Wolfe and colleagues had not yet figured out that part of the frill of Zuniceratops was actually the ischium of what would later be named Nothronychus mckinleyi; and the Crystal Geyser Quarry, which would produce Falcarius, had not yet yielded any recognized therizinosaur material. What made the MNA fossil even more spectacular was its stratigraphic control. It was found in a marine deposit and the bones were actually covered with ammonites!
Shortly afterwards the MNA had some problems and at one point the Geology program was terminated. Fortunately due to public outcry (among other things) the department was reestablished; however, these circumstances caused delays in the study of this specimen. A couple of years ago; however, it was the focus of an excellent new exhibit at the MNA and now the description is finally out. As I have not yet seen the paper I cannot comment on the content but there are some early news reports up here and here. Congrats to Dave Gillette (and to Lindsay Zanno) on the release of the results of this long awaited study. I know that he put a ton of work into this specimen.
You can read an earlier account of this excavation and specimen that came out in Arizona Geology back in the summer of 2007. There is also a good photo gallery of Utah fossils here which includes a reconstruction of N. graffami by artist Victor Leshyk (see photo above), pictures of a display of some of the bones, as well as a picture of Dave in front of a full scale reconstruction done by Rob Gaston.
Since I started at the park in 2001 my students and I have discovered and collected eleven complete and partial skulls, seven of them in the last two summers. Our most recent was discovered this last Tuesday and we were able to get it back to the lab by Wednesday afternoon.
The photo below shows the upper portion of the skull after being exposed. Half of the lower jaw is also present and slightly visible under the boulder to the left.
Below is a photo of the rear portion of the left side of the skull. The squamosal bone (the dark gray mass in the center of the photo) is narrow in dorsal (top) view and deep in lateral (side) view. Thus the skull is almost certainly that of a "Leptosuchus". Interestingly in 1921 Annie Alexander and Charles Camp of the University of California Museum of Paleontology collected the holotype skull of "Machaeroprosopus" ("Leptosuchus") lithodendrorum from a spot close by and at the same stratigraphic horizon.
The forward portion of the lower jaw was in a very hard sandstone matrix underneath a very large boulder at the site. In this third photo you can see the upper part of the skull already plastered and one of my interns is taking a turn under the boulder freeing the lower jaw. We were able to get it out and back to the preparation lab.
This hopefully will prove to be another nice skull for our collections.
ABSTRACT- The anatomy of the palatoquadrate ossifications of the Lower Triassic archosauromorph Proterosuchus fergusi from South Africa is described. It consists of two ossifications, the epipterygoid and the quadrate, which were joined by cartilage in life. The margins of the cartilage are clearly indicated by ridges and grooves on the dorsal surface of the pterygoid. The epipterygoid ossification consists of two structures: the anteroposteriorly expanded basal portion and, dorsally from it, an extending, slender, ascending process. From the anterior margin of the basal portion of the epipterygoid, a plate-like structure, herein called the lamina epipterygoidea anteromedialis, extends anteromedially to form the anterolateral wall of the cavum epiptericum. Comparisons with the similarly constructed embryonal and adult epipterygoid components of Sphenodon punctatus show that the anteromedial lamina of the epipterygoid of P. fergusi is an additional component of the epipterygoid of this species and that this lamina is absent in the former species. However, a structure in a topologically similar position to the anteromedial lamina of the epipterygoid of P. fergusi is present in the palatoquadrate of Alligator mississippiensis. In the latter species, the structure is called the lamina palatoquadrati anterior; it ossifies in membrane and forms the dorsolateral cover of the huge trigeminal ganglion. It is hypothesized here that the anteromedial lamina of the epipterygoid of P. fergusi and the anterior lamina of the palatoquadrate of A. mississippiensis are most probably homologous structures and are present in both the basal and one of the crown taxa of the archosauromorph clade, respectively.
Renesto, S., Spielmann, J.A., and S.G. Lucas. 2009. The oldest record of drepanosaurids (Reptilia, Diapsida) from the Late Triassic (Adamanian Placerias Quarry, Arizona, USA) and the stratigraphic range of the Drepanosauridae. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 252(3):315-325. doi: 10.1127/0077-7749/2009/0252-0315.
ABSTRACT- Previous detailed descriptions of relatively complete drepanosaurid material make it possible to recognize isolated drepanosaurid elements from other localities. The identification of isolated elements from the USA and Great Britain extended the geographical distribution of the group and encouraged a review of Triassic collections for characteristic elements of this family. In this paper, isolated vertebrae previously described as problematic reptiles from the famous Placerias Quarry, near St. Johns, Arizona, USA are re-identified as drepanosaurids. These specimens represent the oldest occurrence of this family, which is earliest Adamanian.
This last paper is interesting as it again demonstates the homogeneous nature of the Chinle Formation faunal assemblages through the lowest to highest fossiliferous exposures. Thus with the exception of dicynodonts the Placerias Quarry, which is stratigraphically low, and contains dicynodonts, possesses pretty much the same faunal elements as the much higher quarries around Ghost Ranch New Mexico (Canjilon, Snyder, Hayden, Coelophysis), which lack dicynodonts. Thus you get phytosaurs, aetosaurs, rauisuchians, poposaurs, Vancleavea, crocodylomorphs, coelophysoids, lagerpetids, and now drepanosaurids throughout the Chinle section. Taxa and abundances in some groups (e.g., metoposaurs) change but the general faunal composition does not. Still, given that the Chinle Formation is now mostly restricted to the Middle and Late Norian (and possibly some of the Rhaetian) this is not too surprising.
Well it looks like PLOS ONE clearly has their act together now regarding the ICZN rules. A section in the new Hocknull et al. paper explicitly lists the libraries where paper copies of the article have been distributed (satisfying ICZN Article 8.6). Furthermore, interested parties can order paper copies for $10 from PLOS ONE. I find this last bit interesting. Of course, with open access papers you can download and print off your own copy; however, in many cases you are at the mercy of the print quality of your printer. Now for a modest fee ($10 in this case) you can get a printed (hopefully reprint quality) copy sent to you. I'm definitely one of the older crowd who still has a hard time reading off a computer screen and love holding an actually printed copy in my hands. Now I may not fork out the $10 for this particular article given that I'm currently not working on Cretaceous sauropods, but if I were I would think that $10 is worth a good hard copy of a 51 page monograph (assuming this is post paid and the quality is good).
Anyhow, kudos to PLOS ONE (and the authors) for recognizing the need to adhere to the current ICZN rules and being so quick to sort out the problem and go above and beyond in solving it. This clearly demonstrates one of the reasons why PLOS ONE is quickly becoming a major player in paleontology publications.
Hocknull, S.A., White, M.A., Tischler, T.R., Cook, A.G., Calleja, N.D., Sloan, T., and D.A. Elliott. 2009. New Mid-Cretaceous (Latest Albian) Dinosaurs from Winton, Queensland, Australia. PLoS ONE 4: e6190. doi:10.1371/journal.pone.0006190
Later that evening, Rachel and my other student intern, Chuck, were able to work on this jigsaw puzzle and we were all pleasantly surprised to see that all of the fragments went together and formed the back of the right side of a phytosaur skull. Even better is that the bone in the upper left corner, the squamosal, is complete and thus we could identify the specimen as a "leptosuchine" phytosaur.
For those of you not familiar with these animals the photo below is a complete skull from a different locality which was found by one of my interns (Joanna) last summer.
The new partial skull is significant because it represents the best phytosaur specimen known from the locality in which it was found. Furthermore, phytosaurs have biostratigraphic significance so this is another data point for the Chinle Formation in the park (more on this at the SVP meeting in Bristol this year).
Finally, this specimen demonstrates the importance of thoroughly investigating all fragments no matter however insignificant they may seem at the time. This was a pile of badly busted up, hematite-encrusted chunks of bone, which actually represents a common condition for fossils found in the Chinle Formation, especially in sandstone units. A lot of patience on the part of Rachel and Chuck and a bit of glue revealed that this scattered mess was actually a scientifically important specimen. Likewise the complete skull found by Joanna last season was only represented on the surface by a small (golf ball circumference) patch of minute bone fragments in the bank of a small wash. Joanna astutely noticed these and carefully followed the fragments into the bank revealing the entire skull!
Also see David Hone's recent post on what a significant find may look like when you first find it.