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Post by creature386 on Jun 19, 2015 20:00:14 GMT 5
Fun fact: One of the authors of that paper (Jens Lallensack) is also a very active contributor in the German Wikipedia. Me and him wrote the Heterodontosaurus article together. Never knew that he's a paleontologist.  On topic, looks like there are again some awesome ichnotaxa theropods. Looks like they were up to 8 m long (what was the size of a T. rex footprint? I assumed 70 cm here). EDIT: Forget my calculation, looks like Tyrannosaurus tracks are more like 80 cm long. I don't know if using that unrelated genera is useful anyway. |
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Post by theropod on Jun 19, 2015 22:03:36 GMT 5
I guess everybody who's ever edited something palaeontological on the German wikipedia will be familiar with that name. Seems like he's at my future university, actually!
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Post by creature386 on Jun 20, 2015 2:42:21 GMT 5
Not if the edit is not about dinosaurs.  But you're right when talking about dinosaurs, I have yet to find a featured or good article there where he didn't provide a significant input. P.S. That kind of off-topic talking between me and you heavily reminds me of my early carnivora days. Nostalgia! |
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Post by Grey on Jun 21, 2015 0:38:54 GMT 5
gsa.confex.com/gsa/2010AM/finalprogram/abstract_181124.htmKILLER SPERM WHALES: EXPLORING THE LIFE HISTORY AND ECOLOGY OF NEOGENE PHYSETERIDS FROM THE ATLANTIC COASTAL PLAIN KILLER SPERM WHALES: EXPLORING THE LIFE HISTORY AND ECOLOGY OF NEOGENE PHYSETERIDS FROM THE ATLANTIC COASTAL PLAIN GILBERT, Kwasi, Earth Sciences, Syracuse University, Heroy Geology Lab, Syracuse, NY 13244, kngilber@syr.edu, IVANY, Linda, Department of Earth Sciences, Syracuse University, Department of Earth Sciences, Syracuse University, Syracuse, NY 13244, and UHEN, Mark D., Atmospheric, Oceanic and Earth Sciences, George Mason University, 4400 University Drive, Fairfax, VA 22030 The Family Physteridae (sperm whales) attained great diversity during the Miocene and Pliocene. Fossil specimens suggest the occurrence of at least 31 distinct species. Within the past decade, several studies have attempted to reconstruct the ecology and phylogeny of these early physeterid taxa, an endeavor made difficult by the scarcity and often poor preservational condition of remains. The Neogene phosphatic sands of the US Atlantic Coastal Plain (ACP), in particular at the Lee Creek Mine, North Carolina, lay claim to one of the largest early physeterid fossil assemblages in the world. Physeterid remains, especially teeth, are common in these strata along with a host of marine vertebrates ranging from turtles to crocodilians. Teeth are known for their archival properties, here we examine the teeth of two physeterid genera, Physeterula and Scalidcetus, to constrain the respective life histories and ecologies of these taxa. Rhythmically accreted growth structures (‘growth layer groups’), analogous to tree rings, are visible in longitudinal cross sections of the teeth. As physeterid teeth grow continuously over ontogeny, these structures can be used to ascertain the age of the animal at death. Tallies of growth increments from multiple individuals reveal that life spans of both Physeterula and Scalidcetus were significantly shorter than the 65+ years noted in modern sperm whales. A relationship between tooth diameter and body size, as established in modern odontocetes, is used to approximate the body size of these early physeterids. Rather than attaining the large body sizes observed in the modern sperm whale, Physeter macrocephalus, these early physterids were comparable in size to modern killer whales, Orcinus orca. Functional upper and lower jaw dentition, not present in the modern taxon, is indicated by wear facets on teeth, suggesting an ecological analog with Orcinus as well. Despite similarities in ecology and body size, life spans of the Lee Creek whales are markedly shorter than those of Orcinus orca. To attain body sizes comparable to those of modern Orcinus in half the time requires rapid growth conceivably facilitated by an abundance of food. The highly productive waters of the ACP at this time likely supplied the resources necessary to sustain the high growth rates and metabolic demands of this top predator.
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Post by Deleted on Jun 28, 2015 21:00:19 GMT 5
Dimetrodon's actual sail may have not looked like what most think. Healed Fractures in the Neural Spines of an Associated Skeleton of Dimetrodon: Implications for Dorsal Sail Morphology and Function"Hyperelongate neural spines forming a prominent dorsal “sail” are known in eight genera distributed between two families of pelycosaurian-grade synapsids. Although the function(s) of the sail remain disputed, most researchers assume that resilient soft tissue stretched between the elongate neural spines, extending to the distal tips. Hypotheses to explain the purpose of the sail have included thermoregulation and sexual selection. In this paper, we analyze the natural pathologies found in the neural spines of a very large pelycosaur, Dimetrodon giganhomogenes, as a natural experiment: What would ensue in the event of sail breakage and what does that tell us about sail structure, development, maintenance, and the orientation of the sail?
A series of seven associated neural spines from FMNH UC 1134 demonstrate subtle though distinctly abnormal rugosities, a sign most often indicative of a well-healed hard callus of bone fracture. Microstructural examination revealed surprising facts: not only did the abnormal bone areas prove NOT to be fracture hard callus, but the abnormal tissue reflected underlying material failure resulting from slippage between adjacent lamellae of bone. Moreover, the characteristic cranial and caudal orientation of the deep longitudinal grooves contributing to the classic dimetrodont figure-8 spine cross section was rapidly reestablished in vivo by a combination of osteoclastic resorption and additional lamellar deposition of bone to regain the “correct” pre-injury orientation, underscoring the architectural importance of the dumbbell shape in resisting lateral bending. This bone disruption and repair occurred at least five seasons before death, which explains the well-healed external appearance of the lesions. The absence of vascular communicating canals casts doubt on the widely held hypothesis that these grooves contained blood vessels that supplied a thermoregulatory sail. Furthermore, the distal morphology of spines in more complete specimens, including the type FMNH UC 112 and OMNH 01727, suggests that the dorsal margin of the sail was located well proximal to the tips of the elongate neural spines. The cross-sectional architecture of the spines suggests a further hypothesis: that the proximal portion of the sail may have also functioned as an energy storage device, facilitating fast locomotion in this top predator." |
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Post by theropod on Jun 28, 2015 21:04:46 GMT 5
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Post by theropod on Jul 8, 2015 21:18:48 GMT 5
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Post by theropod on Jul 17, 2015 15:14:09 GMT 5
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Post by theropod on Jul 18, 2015 23:36:57 GMT 5
babel.hathitrust.org/cgi/pt?id=nyp.33433090912258;view=1up;seq=77Friedrich Huene: Die ichthyosaurier des Lias und ihre zusammenhänge The bad news is that you need to get yourself a fake IP, because the site won’t let you access it if you aren’t in the US, and then you have to download every single page individually, because some ***hole thought there’d be no need to provide the functionality of downloading the whole file to people without institutional access (also only from american universities). The good news, I’ve already done all those steps and built a complete pdf from the pages, so if you’d like a copy, just email me!
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Post by Infinity Blade on Aug 26, 2015 16:43:49 GMT 5
www.sciencedaily.com/releases/2015/08/150812103827.htm"The role of clade competition in the diversification of North American canids"Abstract
The history of biodiversity is characterized by a continual replacement of branches in the tree of life. The rise and demise of these branches (clades) are ultimately determined by changes in speciation and extinction rates, often interpreted as a response to varying abiotic and biotic factors. However, understanding the relative importance of these factors remains a major challenge in evolutionary biology. Here we analyze the rich North American fossil record of the dog family Canidae and of other carnivores to tease apart the roles of competition, body size evolution, and climate change on the sequential replacement of three canid subfamilies (two of which have gone extinct). We develop a novel Bayesian analytic framework to show that competition from multiple carnivore clades successively drove the demise and replacement of the two extinct canid subfamilies by increasing their extinction rates and suppressing their speciation. Competitive effects have likely come from ecologically similar species from both canid and felid clades. These results imply that competition among entire clades, generally considered a rare process, can play a more substantial role than climate change and body size evolution in determining the sequential rise and decline of clades.www.pnas.org/content/112/28/8684
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Post by theropod on Aug 26, 2015 20:46:55 GMT 5
Here: SVP 2015Some pretty interesting abstracts in there. Possible remnants of soft tissue in Dreadnoughtus, vision fields in sauropods, egg colors in dinosaurs, Spinosaurus swimming, and a two-fingered therizinosaur... Also, the quill knobs on Concavenator really are quill knobs based on myological reconstruction. On a similar note: svpca.org/years/2015_southampton/abstracts.pdfI’m sure the presentations concerning the functional anatomy of Spinophorosaurus will be of particular interest to broly, but there’s other interesting stuff. |
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Post by Deleted on Aug 26, 2015 21:28:00 GMT 5
Here: SVP 2015Some pretty interesting abstracts in there. Possible remnants of soft tissue in Dreadnoughtus, vision fields in sauropods, egg colors in dinosaurs, Spinosaurus swimming, and a two-fingered therizinosaur... Also, the quill knobs on Concavenator really are quill knobs based on myological reconstruction. On a similar note: svpca.org/years/2015_southampton/abstracts.pdfI’m sure the presentations concerning the functional anatomy of Spinophorosaurus will be of particular interest to broly, but there’s other interesting stuff. I read it and it seems that it no longer has tail spikes but instead a rather muscular tail with some little similarities to diplodocoid tails, if I'm reading those right. |
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Post by Grey on Oct 9, 2015 23:53:03 GMT 5
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Post by Deleted on Oct 19, 2015 0:09:29 GMT 5
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Post by Grey on Oct 19, 2015 0:44:36 GMT 5
Calcium isotopesreveal the trophic position of extant and fossil elasmobranchs
Jeremy E. Martin, Th´eo Tacail, Sylvain Adnet, Catherine Girard, Vincent
BalterRecent calcium isotope studies recovered a trophic level effect in marine ecosystems. However, elasmobranchs are virtually absent from such studies despite their important ecological role, their diversity and their extensive fossil record. Enameloid of extant elasmobranchs representing differing known ecologies were measured for δ44/42Ca. The results reveal that their calcium isotope values have a distribution (from – 0.27 to – 0.78 ‰) that follow a stepwise decrease (∆ 44/42Ca) of about – 0.14 ‰ across recognizedtrophic levels: zooplanktivores, primary, secondary, and tertiary consumers. Although the recovered calcium isotope distributions partly match the ecological divisions of extant elasmobranchs, data for marine mammals are more variable and cannot be explained by trophic segregation alone. Nevertheless, our results reopen perspectives for the study of ancient marine assemblages using calcium isotopes. As a case study, the calcium isotope values of a Pliocene fish assemblage parallels the results obtained from extant elasmobranchs and allow inferring that the giant shark Megaselachus megalodon fed at a slightly higher trophic level than the contemporaneous Great White shark. app.box.com/s/liz1w40n1f895y1ggilr65oyx4cj87uf
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