Archive for January, 2010



Ossified tendons

Let’s face it, although it would be far less catchy it would be more accurate to call this the ‘theropod and pterosaur and occasionally other things’ blog more than the Archosaur Musings, but since that is where my knowledge and interests lie, that’s what you tend to get. However I am trying to at least get some more ornithischians, birds and crocs in here but bear with me if it takes a while and tends to be short.

Here though I want to mention one defining characteristic of the Ornithischia as it actually relates to both theropods and pterosaurs, if rather obliquely, namely the ossified tendons of the spine. Many of you are probably familiar with these already since they crop up in various ecological and mechanical discussions about how tails work (especially with the old one about hadrosaurs swimming). For those who don’t however, the short version is that ornithischians have a series of elongate little bones that run alongside the vertebral column, especially close to the sacrum.

I say ‘bones’ and in a sense they are, though they are not like normal skeletal elements but are tendons that have been turned into bones. This is actually more familiar that you might think – you may well have noticed how tough some tendons are in a turkey carcass compared to a chicken and this is a result of the same process. Ossified tendons are quite literally those that are partially, or fully turned to bony tissue. Those tendons that take heavy loads often have this happen to them as seen in turkeys or for an extinct examplw the nyctosaurid pterosaurs.

These are present in pretty much all ornithischians (stegosaurs don’t have them), though don’t always show up in juvenile animals and some have far more than others. They are typically concentrated on the vertebrae of the sacrum but do appear on the dorsals and caudals too in most cases. They are typically long and thin and lie subparallel to each other, though famously in the hadrosaurs they form a lattice work on the tail. Here’s a not very good image showing then in Psittacosaurus (above) and Yinlong (below). In the former they appear as a series of stripes and in the latter as some rods (though badly broken) but between the two it should give you an idea of what I mena and demonstrate that they are not part of the vertebrae themselves.

So, where’s the relevance to dromaeosaurs and pterosaurs? Well in some cases, (with Tianyulong being a notable example) there can be loads of ossified tendons binding the tail up in a tight mass of little splints of bone. This can look very similar to the situation in both dromaeosaurs and some rhamphorhynchoid pterosaurs where the tail is similarly bound up. However, in the latter cases this is a result of those (normally) little articulations on the vertebrae (the pre and postzygopophyses) being enormously extended into long thin rods. The tails can therefore look superficially similar between the two groups, but close examination should reveal the fact that in the ornithischians, the rods of bone are not part of the vertebrae by lying on top of them. It’s actually a rather nice demonstration of solving the same problem (stiffening the tail in this case) in two different ways as well as the convergence between the dromaeosaur and rhamphorhynchoid tails.

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A guide for journalists reporting on dinosaur stories

Since I spend so much time berating the media for their terrible coverage of dinosaur-related stories I thought I should try and add a little positivity / advice rather than *just* slating them. In that light then, here are a few errors that seem to be made time after time after time and should be really easy to fix. Obviously I doubt I have many, if any, readers who are also science journalists (of the kind that make lots of basic errors, many are very good) but a) you never know your luck and b) I might just use this in the future when I next send out a press release to try and get things straight. This is, I am sure, very obvious to many, but these kinds of errors occur too often for it to be chance alone, so a few pointers may prove helpful (and will likely be of interest to other readers too).
Continue reading ‘A guide for journalists reporting on dinosaur stories’

The most magical bone in China

There’s really not much I can add to this title and this photo.

Yet another post on Dsungaripterus

Yes I know there have been a few of these of late, but hell there’s lots of material and reconstructions on display and I do like pterosaurs. However, where before this tended to manifest itself on various casts this time we can go to both extremes. First off, an actual original skull and one of CC Young’s type specimens) from the IVPP which should be an improvement on the previous posts.

Secondly there is this rather nice painting of Dsungaripterus that hangs in the IVPP museum though annoyingly with no indication of who did it or when. I rather assume it’s quite old and was probably done to coincide with the description or mounting of the original material. Still, it’s pretty good and I’ve never seen it reproduced anywhere else so seemed a nice little feature to cover.

On thing that is perhaps worth commenting on is the crest. As has been noted before, while a great many pterosaurs do indeed have a variety of bony crests quite a few also combined bone with soft tissues and these often have a pretty distinctive bone texture. As such even when the preservation of the specimen means you wouldn’t get any softs preserved, it’s pretty likely that they were there in life. Dsungaripterus is one such example where the bony crest is pretty short but has all the hallmarks of having something rather bigger attached. While this is illustrated very occasionally (like the banner on here for starters) it’s very rarely seen, despite the good evidence we have for it. Another small example of pterosaur representation lagging behind the actual science.

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Some dinosaur documentaries

I came across this list of free online science documentaries today. There’s half a dozen ones on dinosaurs as well as various ones on evolution and other issues that may be of interest. Enjoy.

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Bellusaurus

Continuing the quite long series of short posts covering all manner of IVPP material we have the very little studied and perhaps even more rarely seen Bellusaurus. Pictured is one of two mounts at the IVPP, though neither are great and the bones are largely obscured.

Bellusaurus is known from the Middle Jurassic and comes from western China in the area that I have so far yet to visit as part of my field seasons in China due to various permit problems. There are apparently quite a few specimens known, though I’ve not come across any in our main collections (not that I have gone looking) though at least there are bits of two on display which is more than I can say for the amount of information available in the literature which seems conspicuous by its absence.

The animals are clearly small (about 4m in total length) and have been suggested to be juveniles by people who a) know sauropods much better than me and b) have seen the material. Still, I couldn’t spot any obvious indicators of them being youngsters on the admittedly poor mounts, so I’d suggest that it’s at least possible that this is, if not an adult size, close to it. There are other sauropods out there that are closer to this is size so it’d be a surprise, but not a shock.

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Not there

Having touched on mounts for dinosaur skeletons before, it’s about time I dragged out these images from my first visit to China back in 2006. First off here’s a bare metal frame set to have a sauropod skeleton mounted on it. This was obviously custom made for the skeleton / casts to be attached, though I forget which taxon it was now. Each bone had it’s own little cradle that then bolts or crews into the main frame and thus the whole thing can be assembled and taken apart to move it as necessary.

The second photo is of me with a half finished mount of Mamenchisaurus. As you can see some, but far from all, of the bones have been bolted onto some of the frame. Naturally this takes quite a while and on something this scale, getting all of the neck vertebrae and especially the skull in place can be pretty tricky.

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Accessing specimens

With apologies to John Cleese and Graham Chapman and following a conversation with Jonah Choiniere:

Continue reading ‘Accessing specimens’

And so Pterosaur.Net took wing

A Rey Pterodactylus

Long time readers will know that a couple of times on here I’ve promised a ‘new pterosaur website’ that never quite appeared and those with clicky fingers might well have spotted the link to a site called Pterosaur.Net lurking around on here. Well, I can now officially announce that the long awaited Pterosaur.Net has at last taken off and soared onto the web.

If you have been over there in the past (and i know some have) you will have seen various incomplete and half constructed versions, but this is pretty much the finished deal and while we do hope to make a few more additions the site is essentially done. First and foremost, full credit to John Conway for the design and execution, though there are a large number of contributors to the site. So if you want to read Mark Witton’s review of pterosaur ecology, Darren Naish on crypto-pterosaurs, Mike Habib on the mechanics of flight, myself on pterosaur origins and relationships and Dino Frey, Ross Elgin and others get stuck into various taxa then get on over there. You’ll also find artwork by John, Mark and Luis Rey and all manner of pterosaur specimens including lots of new UV work by Helmut Tischlinger and we were able to get permission from a number of institutes to publish images of important fossils, some of which are rarely illustrated. There’s also an integrated blog on the site which hopefully will be updated regularly with various posts from the contributors.

Pterosaur.net is however rather different to the various other projects that I’ve put together or worked on before in that it is largely supposed to be a ‘static’ information site, as opposed to a blog, forum or other more ongoing or interactive website. The reason for this goes back to the origins of Pterosaur.Net which started outside a cafe in Munich back in 2007 and the Wellnhofer Pterosaur Meeting.

Wavy lines.

Continue reading ‘And so Pterosaur.Net took wing’

Mesozoic Birds

While obviously the title of the blog covers birds, they get rather short shrift on here as I try to focus on the Mesozoic archosaurs. However, even this definition doesn’t rule out all the various birds that lived in the Jurassic and Cretaceous. Here then are a couple of them, first off (above) a not-that-great photo of the not-that-great holotype specimen of Jeholornis.

Secondly (above and below) the near ubiquitous Confuscisornis. I’ve seen well over a hundred specimens of this without having troubled many of the museums in Liaoning that have extensive birds collections so it’s a pretty safe bet that there are several hundred specimens of this in China and probably well into the thousands when private collections are taken into account. Although I’ve not heard of anyone actually trying to crunch the numbers, I’d not be surprised if it was one of the most common tetraopods from Liaoning (certainly apart from a couple of the amphibians and near infinite hyphalosaurs) and there seem to be few museums now, inside or outside China, that don’t have a specimen or two somewhere.

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Magnirostris – it’s not Protoceratops

When out at Bayan Mandahu and a few other similar localities the one thing you are bound to find is Protoceratops. This little ceratopsian is present in huge numbers and there are all kinds of fossils out there of it and lots of teeth too. It was by far the most common animal out there and it’s a reasonable bet that any unidentified scrap of bone that you find out there ultimately come from a Protoceratops.

However, to confuse matters just a little there is the extraordinarily similar Bagaceratops present and a few other taxa that may or may not be valid depending on quite whom you ask. This skull is from the putative genus Magnirostris named in 2003 but already considered likely to be a juvenile Bagaceratops. I’m certainly not in a position to delve into the taxonomy of the ceratopsians (nor do I especially want to) but it’s a really nice skull and was worth putting up.

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Pinacosaurus

Another short post on IVPP ornithischians and time for a return to the most armoured of armoured dinosaurs – the anyklosaurs. This is a specimen of a very young Pinacosaurus and the whole specimen is only about 20 cm long, so the whole animal would have been well under a metre in life. Even so the various armoured plates are already quite thick and tough and you can see the ‘box-head’ structure appearing on the skull and the various bands of armour over the neck and back.

Pinacosaurs is really quite common out at Bayan Mandahu, so much so that the first dinosaur specimen I ever found was a piece of jaw with some teeth in belonging to a young animal. We found a number of largely complete individuals last year and this is not uncommon with the Sino-Canadian Dinosaur Project team uncovering quite a few in the 1980s. Like other ankylosaurs the taxonomy is not in the best of shape but I know work is underway on a revision and redescription of several specimens to sort out the names so hopefully will be complete to everyone’s satisfaction in a year or two.

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