Carrano and Choiniere reexamine Ceratosaurus' forelimb based on the holotype. The whole thing could use redescription since Gilmore's last one 95 years ago. While they state "These new data are consistent with the placement of Ceratosaurus as close to (or within) Abelisauroidea", an abelisauroid Ceratosaurus is impossible as Ceratosauroidea predates Abelisauroidea, without even getting into phylogenetic nomenclature.
Hey, we get more Dromiceiomimus feathers. van der Reest et al. report on a new specimen preserving feathers on the proximal thigh and dorsal tail, but not ventral tail or distal hindlimb. The feathers are also branched, moving this trait to the base of Maniraptoriformes. As the feathers have rachis but lack barbules, it seems Prum's Stage IIIa was correct.
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| Segnosaurus galbinensis radius and ulna (paratype IGM 100/83), courtesy of Zanno. |
Kobayashi et al. describe a new therizinosaur specimen from the Bayan Shiree Formation, where Segnosaurus, Erlikosaurus and Enigmosaurus come from. While it's notable for having a reduced metacarpal III (and thus perhaps reduced third manual digit), none of the three named genera from that formation preserve enough manual material to evaluate their condition. The new specimen is potentially comparable to Enigmosaurus and Segnosaurus in that all preserve the radius and ulna.
Funston and Currie report on their fairly complete Horseshoe Canyon caenagnathid. Supposedly having cervicals "distinct from Epichirostenotes", an "articular ridge is intermediate in size and form between Caenagnathus collinsi" and sternbergi, and autapomorphic manual proportions, it should be useful for resolving caenagnathid taxonomy. In addition to the expected anatomical details, ulnar "feather scars" are said to be present.
Lu et al. discuss the billionth new oviraptorid from the Nanxiong Formation. This one's based on at least a skull and is similar to Khaan. Some of these things have got to be synonymous
Saurornitholestes has been the ubiquitous but rarely described Late Cretaceous American dromaeosaurid. We've had RTMP 88.121.39 and MOR 660 known since 1988 and 1990 respectively, but both are only mentioned in passing in papers. Now we have a new almost complete specimen discovered in 2014 (did anyone who saw the talk catch the specimen number?) that includes a skull. Is the Saurornitholestes osteology finally at hand?
Perhaps the most unusual theropod abstract is from Sorkin, describing a phylogeny for tetanurines. I'm not sure if it's based on a quantitative analysis or just the noted 'key characters', but it's not similar to the current consensus. From the abstract, his topology and taxonomy seems to be-
|--Ceratosauria
`--Tetanurae
|--Spinosauridae
|--Carcharodontosauridae
`--+--Sinosaurus
|--Piatnitzkysauridae
|--Metriacanthosauridae
|--Neovenator
|--Megaraptora
`--Avetheropoda
|--Megalosauridae
`--Euavetheropoda
|--Monolophosaurus
|--Acrocanthosauridae (incl. Eocarcharia)
`--+--Allosauridae
`--Coelurosauria
Brings you back to the early 90s, doesn't it? Note the new clade name Euavetheropoda, said to be distinguished by a robust dorsal quadratojugal process. In any case, the accepted phylogenetic definition for Avetheropoda would put it at the Allosauridae+Coelurosauria node, making Euavetheropoda unintuitively more inclusive.
Wills describes sixteen teeth from the Bathonian Forest Marble Formation of England. When analyzed, these plot with dromaeosaurids. He states "This pushes back the origin of dromaeosaurids from the Kimmeridgian to the Bathonian", but Metcalf and Walker described teeth from the Bathonian Chipping Norton Formation of England as dromaseosaur-like back in 1994. Maybe these new ones are more securely identified.
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| Dromaeosaurid-like tooth (GLRCM G.51422) from the Bathonian Chipping Norton Formation in lingual (A), labial (B) and basal (C) views (after Metcalf and Walker, 1994). |
Reference- Metcalf and Walker, 1994. A new Bathonian microvertebrate locality in the English Midlands. In Fraser and Sues (eds.). In the Shadow of the Dinosaurs- Mesozoic Small Tetrapods. Cambridge University Press. 322-332.
"Saurornitholestes has been the ubiquitous but rarely described Late Cretaceous American dromaeosaurid. We've had RTMP 88.121.39 and MOR 660 known since 1988 and 1990 respectively, but both are only mentioned in passing in papers. Now we have a new almost complete specimen discovered in 2014 (did anyone who saw the talk catch the specimen number?) that includes a skull. Is the Saurornitholestes osteology finally at hand?"
ReplyDeleteI don't know the specimen number and I wasn't at the talk, but I may know the specimen. What institution prepared it, and how well was it preserved?
I learned what it was- UALVP 55700. Similarly, the feathered Dromiceiomimus is UALVP 52531.
DeletePS: Actually, with Albertonykus describing it as really well preserved and saying that Phil Currie described it, I'm pretty sure I know what it is. I got to see it when I was working in Alberta over the summer thanks to a friend of mine at U of A. If there's anything you'd like to know about it, I don't think they'd want me posting it on social media, but I can arrange contact info.
ReplyDeleteCarrano and Choiniere reexamine Ceratosaurus' forelimb based on the holotype.
ReplyDeleteThe take-home message is that the pattern of limb reduction seen in Limusaurus is a ceratosaurian autapomorphy and irrelevant to Tetanurae.
Is the Saurornitholestes osteology finally at hand?
Yes.
Carrano and Choiniere's abstract has now been published --- see http://www.tandfonline.com/doi/full/10.1080/02724634.2015.1054497.
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