From the grave to the cradle

This is the arm of the Dryosaurus skeleton I put up earlier in the week. You can see here quite clearly that the bones are held in ‘cradles’ that then are bolted onto the main support for the skeleton. This technique for mounting specimens has become popular recently (the remodeled dinosaur gallery in the Humboldt in Berlin uses the same methods) and it’s a welcome change from the old style. The bones used to be bolted directly to the frame meaning that they were often drilled through or had rods and bolts put through the bones themselves.

Obviously this is infinitely preferable to any form of damage or manipulation of the bones. It allows them to be put out on public exhibition, but it *also* allows them to be removed as single units as the cradles can be simply taken off the frame, and the whole thing doesn’t have to be taken apart to get to a single element. As a compromise, it’s relaly pretty good.

Lufengosaurus

After that hadrosaur the other day, I thought I’d stick up an unambiguous skull. This is of Lufengosaurus, a pretty small basal sauropodomoph (or ‘prosauropod’ if you prefer) from southern China. Actually I have a sneaking suspicion it’s the holotype but I don’t actually know for sure. It is part of an essentially complete and mounted skeleton that’s on display at the IVPP though the individual bones have taken quite a battering.

Prosauropods don’t seem to get much love in general. I suppose they don’t have the supersize of their cousins, aren’t predators like theropods or sport such weird and wonderful ornaments like most of the ornithischians. So it’s nice to give them a bit of coverage here and I have a raft of Plateosaurus photos I must get round to putting up, though that seems a bit redundant these days with Henrich Mallison now a blogger too. After all, what can I possibly say about this animal compared to what he’s already put up?

Camplognathoides

Bit of a late one today! I’m slipping.

Anyway, this is the horrible-to-spell Campylognathoides, a basal non-pterodasctyloid pterosaur known from Lower Jurassic beds. This is an especially nice specimen that’s on display in the Carnegie (how did you guess) and shows off things like the sternum which is all too rare for pterosaurs.

One thing Campylognathoides does give me the opportunity to talk about is pterosaur systemtics. Those in the know will be aware that for about a decade now there have basically been two competing pterosaur phylognies that have fundamental differences and never seem to meet in the middle (though there have been suggestions that Darwinopterus might just fix this issue). However, as Dave Uniwn is fond of saying (and quite rightly) for all that people highlight the disagreements between these phylogenies, there is really quite a lot of fundamental agreement, and the two trees are in a lot of ways really pretty congruent. One thing that is certainly common in both is the sister-taxon relationship of Campylognathoides with Eudimorphodon and that at least is one thing it appears pretty much everyone agrees on.

I call the big one ‘Bitey’

You wait years for a Musings croc post and then get get two withing a couple of months. Who’d have guessed eh? Well, none too exciting given the lack of scale bars and all since it makes it harder to appreciate just how big these are, but this is a dorsal and some osteoderms from the colossal croc Deinosuchus. The north African Sarcosuchus seems to get all the press, but this animal was of similar size and has a more typical (and thus likely more powerful) skull than the rather gharial-like Sarco. As noted, it’s hard to appreciate here, but the biggest osteoderm was about the size of my hand. This was a really serious animal.

Darren Tanke’s Gorgosaurus preparation 32: Removing the field jacket 2

Some pieces come off in large sections. A block of wood is useful as a fulcrum with the screwdriver(s) to pry up the plaster bandages. After 1.5 days of pulling and tearing, most of the jacket was off, rock was showing and the ilium uncovered in the field was also seen again for the first time in several years. The skull was outlined again with a red felt pen using the drilled holes. As the jacket got thinner, a quite large piece wanted to lift off the skull area. This was too big, so I used a cast cutter to cut two parallel lines through the jacket and pulled out the plaster and burlap in between.

This separated the remaining jacket into two pieces and the plaster/burlap covering the skull section was lifted off easily. By doing this, the jacketed skull was seen. The rags and black plastic sheeting was exposed and removed- the latter with a razor blade. The skull jacket looks odd with white sandstone and dark brown mud, but the latter was a poultice I mixed up and put on the exposed snout to protect it from the jacket- I did not want the jacket pressed right against the skull.

The poultice of dried mud was removed and preparation on the skull begun again. The skull is definately incomplete on this side and the bone seems more poorly preserved- the bone is very splintery. Several of the teeth show white meandering markings (root etchings) made by modern plants as they grew against the specimen. It is thought the roots leach minerals out of the fossil with possible negative effects on the fossil. The rest of the exposed rock was allowed to dry out and when done, glue was squirted into the cracks, etc to stabilize it for the upcoming preparation.

Fieldwork for me starts very soon so these will likely be the last postings from me for some time. [Actually Darren has already gone I think, I’ve just had this sat waiting for a while].

Dinosaur skin

Obviously I have covered feathers on dinosaurs here several times, so it’s about time we looked at non-feather integuments, or to be less jargon-y, skin. This picture is of a rather nicely preserved piece of dinosaur skin on display at the Geological Museum of China. Sadly they don’t list which taxon or fossil site it is from and I keep forgetting to ask them. However, based on its size (the small scales are only a couple of millimeters across), similarity of form to others in the clade and frequency of the specimens in the formation from which most of the museum’s specimens come, I suspect it’s a ceratopsian of some kind, quite probably Psittacosaurus.

I’m no expert on skin so I could be wrong, but the important point here is that a) it looks nice, b) it therefore shows off just how good evidence we have for what some dinosaur skin looked like, c) how good the fossil preservation is and d) what the actual pattern of the skin was like. Here at least you can draw a great deal of information on skin and scale pattern and structure. What you can’t do however is say exactly what animal it came from, or from what part of the body.

This piece is in isolation – it’s just a piece of skin on a rock. As such despite it resembling ceratopsians (to my eye at least, or even if we had a pretty much exact match to another known taxon) we really can’t say for sure what it came from. Nor do we know where on the body it would have gone – we can probably rule out the soles of the feet and the head but after that it could be leg, tail, back, even belly. This is important as of course there are significant variations in skin patterns not just in modern reptiles but birds too and also in dinosaurs. As such, it’s good, but hardly great, though still worth enjoying.

Obviously I have covered feathers on dinosaurs here several times, so it’s about time we looked at non-feather integuments, or to be less jargon-y, skin. This picture is of a rather nicely preserved piece of dinosaur skin on display at the Geological Museum of China. Sadly they don’t list which taxon or fossil site it is from and I keep forgetting to ask them. However, based on its size (the small scales are only a couple of millimeters across), similarity of form to others in the clade and frequency of the specimens in the formation from which most of the museum’s specimens come, I suspect it’s a ceratopsian of some kind, quite probably Psittacosaurus.