Readers will remember a beautiful fossil from the Solnhofen being shown on here back in November of last year. People who have access to the internet will probably now now that yesterday the first formal publication on this animal came out. It’s now named Sciurumimus – the squirrel mimic – on account of the rather bushy tail. There’s already a ton of discussion on this online and quite some hefty coverage so I’m not going to dive into the ins and outs of feather distribution in theropods or the phylogenetic position of it. It is worth comparing it to Juraventor of course – sister-taxon to Sciurumimus in the analysis and from the same beds. Despite the obvious gross similarities, the authors do note a ton of small differences between the two that suggest they are genuinely distinct.
Of much more interest to the readers though will be the fact that once more Helmut Tischlinger has been generous enough to send me a variety of nice images with permission to publish them here. At least one of these isn’t in the paper and the res is pretty good so even those of you who’ve been able to peruse the PNAS paper might do well here, so enjoy. As usual my thanks to him for this very generous act and a reminder that these are his images and should not be reproduced without permission etc.
Dave Hone's Archosaur Musings 
Thanks so much to you and Helmut Tischlinger for sharing these images, especially since the paper is behind a PNAS paywall.
Yup, thanks for sharing these! Appreciate the high resolution shots that highlight the feathers.
Lovely pics. Thanks Helmut and Dave.
Hasn’t Sciurumimus been identified as a megalosauroid whilst Juravenator is generally considered to be a coelurosaur? If the authors consider them to be sister taxa then one of these things has to change (I can’t see what they say for myself as the paper is paywalled).
Juravenator moves. They find them to be sister-taxa, but both as megalosauroids.
I was suprised to read that the species name is in honor of the the private collector that made the specimen available fo study. As a layman I had been told that scientific journals would not accept papers about taxa in private hands since there was no assurance that they would be available for follow-up study.
Is this incorrect?
My understanding is that it’s been donated to the museum (it does have a formal museum number) so that this is more a bad phrasing that anything. He made it available for study yes, but it’s also permanently in a proper collection.
Thanks, turning to the general from the specific.
Is it true that a journal will not accept a paper about taxa that remain in private collections?
Not quite. Lots of journals simply will not accept anything on private material (JVP won’t even allow datapoints from private specimens) but some do get through for various exceptional circumstances. Chris Bennett’s paper on Nyctosaurus is a good example – the key specimens were, and remain, in private hands. But casts and photos were deposited in museum archives and Chris limited his paper only to one key feature of the private specimens (the crests) which could be revealed. In short, it’s not impossible, but it is unusual and generally requires there to be some large extenuating circumstances or unusual situation.
Thanks for clearing that up, Dave.
I just saw the pics on yahoo news. It has been suggested that Yixian dinosaurs became feathered during a cold spell in China; cooling is also said to have occurred in the late Jurassic, which may explain Sciurumimus. Or maybe the need for insulation was most acute in juveniles.
Tim: I do not buy the argument that “Yixian dinos were feathered because of coolness”. To me the data is far more easily explained by taphonomic filters: we only see fuzz where it can be preserved. My prediction: if we have lacustrine and lagoonal deposits in the Morrison, the Hell Creek, or wherever, we’d see the fuzz.
I wince whenever I see juvenile archosaurs, even complete specimens, described as new species, let alone new genera. Given the relative paucity of the fossil record, it seems like a big leap of faith to prescribe novel taxonomic label to baby dinosaurs, birds, and pterosaurs, especially since our knowledge of their ontogenic and isometric development is still far from complete. So shouldn’t we leave “Juravenator” and “Sciurumimus” as “Tetanurae incertae sedis” until other, more mature specimens are found?
But that assumes we will find more adult specimens. Compsoganthus has been around for a century and we’ve done a *lot* of digging in Southern Germany and no sign of a more mature animal. And while we don’t have a complete picture of ontogeny, it’s pretty good for as lot of things – at least good enough to know that some characters don’t change or don’t change much during ontogeny and so are taxonomically reliable. As long as you’re careful, it’s generally fine.
Compsognathus longipes is different in that, despite the lack of mature specimens from Solholfen and other German sites, we have a fairly good picture of the adults thanks to the “Comsognathus corallestris” remains from France. With “Juravenator” and “Sciurumimus”, however, there current lack of a definite adult analogue in the region. Additionally, the reassignment of the two taxa from Compsognathidae to Megalosauroidea raises inevitable questions on the effectiveness of taxonomic diagnosis based on the ontogenic “stasis” of certain anatomical features. I’m not saying the methodology is invalid, but it may not work as well for non-avian theropods as it does for, say, marginocephalians and ornithopods.
Sorry but that doesn’t work. C. longipipes was named before the frqanch specimne turned up. And in any case, is a different species to C. corallastris (and may be a different genus). The issues is in general can / should juveniles be named and I (and indeed every palaeontologist I know) thinks they can, it simply requires some care.
What is the red arrow pointing out?
Some of the very long feathers in the tail, if you look closely there are some very fine yellowy-green lines that represent them.
Very cool. I’m a novice and am learning a lot. The skull seems different than what I’ve seen in other dinos. I think I see the opening between nose and eye, but not sure I see the temporal openings that make it a diapsid.
They often aren’t visible. In things like ankylosaurs and birds for example, they can be closed so aren’t there to be seen. The upper temporal fenestra is usually on the top of the skull, so in a flat specimen like this seen from the side, it’ll be hidden. Finally remember that in this view the braincase and other parts of the skull will be in the way and mark it. The kind of drawings you see in text books are trying to make the fenestra super clear and won’t show anything that might make them hard to see. reality is not always as clear.