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hey everyone - hope you're all well Thought this was worth sharing - a description of a well-preserved enantiornithean bird specimen from the Late Cretaceous Kaiparowits Formation of Utah. It represents a new genus and species, Mirarce eatoni. The specimen was originally collected in 1992, but it was only recently described (and published yesterday!). Atterholt et al. (2018). The most complete enantiornithine from North America and a phylogenetic analysis of the Avisauridae. PeerJ, DOI 10.7717/peerj.5910 Abstract: The most complete known North American enantiornithine was collected in 1992 but never formally described. The so-called “Kaiparowits avisaurid” remains one of the most exceptional Late Cretaceous enantiornithine fossils. We recognize this specimen as a new taxon, Mirarce eatoni (gen. et sp. nov.), and provide a complete anatomical description. We maintain that the specimen is referable to the Avisauridae, a clade previously only known in North America from isolated tarsometatarsi. Information from this specimen helps to clarify evolutionary trends within the Enantiornithes. Its large body size supports previously observed trends toward larger body mass in the Late Cretaceous. However, trends toward increased fusion of compound elements across the clade as a whole are weak compared to the Ornithuromorpha. The new specimen reveals for the first time the presence of remige papillae in the enantiornithines, indicating this feature was evolved in parallel to dromaeosaurids and derived ornithuromorphs. Although morphology of the pygostyle and (to a lesser degree) the coracoid and manus appear to remain fairly static during the 65 million years plus of enantiornithine evolution, by the end of the Mesozoic at least some enantiornithine birds had evolved several features convergent with the Neornithes including a deeply keeled sternum, a narrow furcula with a short hypocleidium, and ulnar quill knobs—all features that indicate refinement of theflight apparatus and increased aerial abilities. We conduct the first cladistic analysis to include all purported avisuarid enantiornithines, recovering an Avisauridae consisting of a dichotomy between North and South American taxa. Based on morphological observations and supported by cladistic analysis, we demonstrate Avisaurus to be paraphyletic and erect a new genus for “A. gloriae,” Gettyia gen. nov. here's the paper: Atterholt et al. Hope you like it! -Christian
Hey everyone, I recently came back from a trip to England. Most of the time was spent in museums, especially London's Natural History Museum. Over there, I met the Curator of Invertebrate Paleontology (Tim Ewin), who showed me around some parts of the Echinoderm Collections. Basically, the goal of this visit was to examine some of the echinoderms from the British Chalk, for some comparative research material for my MKFRP project. Some of the stuff in those collections is absolutely amazing - and the amount of material in there is really extensive. This thread will show some of the chalk echinoderm material that I saw over there. Hope you guys'll like this! 2 very well articulated Tylocidaris clavigera in a single nodule of chalk g on Drawer filled with "tylocidarine" regular echinoids. The pink colouring on some of the specimens is due to the fact that some of them needed to have the fine details rendered sharper (this was before the age of digital photography) Partial Tylocidaris clavigera associated with a disarticulated goniasterid (Asteroidea, Goniasteridae) starfish Very well preserved and nearly complete Nymphaster marginatus goniasterid Neat little example of the goniasterid Metopaster Calyx and partial arm of the free-floating crinoid Marsupites testudinarius (sorry for not very good photo quality ) Articulated columnals of an isocrinid crinoid (possibly Isocrinus); this is specifically relevant to my MKFRP project given the age of that fossil (Early Maastrichtian) To finish things off… It's not very "chalk-y", but it's definitely special - a Palaeocoma milleri ophiuroid from the Early Jurassic of Lyme Regis, collected by Mary Anning
Hi everyone! I found this this bone while digging in the Hell Creek formation on a ranch in Montana. Any idea what it might be? Has some really unusual texture in a few places that I've not seen before. Could it be some kind of metatarsal bone? Was found alongside a fair bit of triceratops bone as well as a Thescelosaurus femur and some pieces of T-Rex. What might the strange texture be? Based on the rounded edges on both sides (minus a small chunk that's missing) it looks to be nearly complete...I think?? Thank you! -Lauren