Archive for February, 2011

Time Travel

Apparently not content with my time traveling research, a comment posted the other day asked the delightfully intriguing question of: “If you could travel back in time what are the five top things you’d want to check out in the field?”. Wow, and cool!

I can see this becoming a meme of some kind so I’ll stick to / create a few rules. I’ll only talk about things that really interest me. If I really only had 5 shots at this, I’d probably do some things that would genuinely help science and go looking at early hominids or vertebrates or whatever, but that’s too general and non-specific. I’ll also assume that I couldn’t bring anything substantial back with me – a bone or a blood sample is fine to do some genetics work or compare things in the lab, but no herds of sauropods. I should be in a position to travel freely and make general observations and simple analyses (so even if it’s not obviously clear, that I could say tell males from females, or identify cryptic species etc. Finally, I’ll cheat a bit and allow single ‘trips’ to take some time (like a few million years where necessary) and consider them more ‘observations of single events’ than ‘going somewhere / when for 24 hours’, so by that definition going to see the KT extinction is fine, or watching the transition from Ambulocetus to Basilosaurus is OK. Bearing that in mind, here’s the 5 things i’d be checking out if I could:

1. The origin of flight in birds. OK this is almost a cliche, but this is well within the reals of my research and I really would love to see how those first gliders / parachuters / protobirds got going and where they started from (up or down) and if there really were multiple origins of powered flight in different lineages.

2. The predation habits of theropods in the Kem Kem. I’m picking this specifically because it’s (possibly) a weird ecosystem but more importantly I could get to see a nice big range of different taxa all together and look at their ecological partitioning and exactly what they hunted and scavenged and how (the juveniles, obviously!).

3. Just a general visit to the Jehol biota. I really want to see a proper, functioning, diverse, dinosaurina ecosystem and this has everything. Birds, pterosaurs, big and small dinosaurs of all kinds, odd mammals and the rest.

4. The pterosaur transition from rhamphorhynchoid to pterodactyloid. Obviously that includes Darwinopterus and the like, but what exactly happened here, did the head really go in one big chunk or did that take ages with various changes in sequence before the body played catch-up and what was the tail doing?

5. Quetzalcoatlus locomotion. Pure personal thrill on this one. I’ve been lucky enough to see wild condors at very close range flying around and it was absolutely incredible. I just must see something 3 times that size get into the air and cruise around. A natural history phenomenon.

An announcement

This post is a private / public admonishment of someone on the palaeo scene. It’s private because I won’t name names and draw public attention to him. It’s public because I’m doing it on the blog. (and in case you were wondering, I’m not mailing the person concerned directly because I have had several unproductive exchanges in the past and have deliberately severed all contact with them and have no wish to resurect that).

Continue reading ‘An announcement’

Gorgosaurus reconstruction

Although the final roundup of the great Gorgosaurus preparation series went up last week, there is a late entry. Darren was sent this rather natty reconstruction of Gorgosaurus by Eric Warren and he passed it onto me and of course me onto you all.

Taxonomy never stops

It’s hard to tell if this is a misconception about taxonomy as it never seems to even be mentioned conceptually, but I suspect it is one, or at least is never even thought about. Taxonomy quite simply does not stop with the naming of a new species. While this is perhaps the most obvious, and arguably most important, aspect getting a new species named is just the start. Now I’m sure that most readers by now will be familiar with the various arguments about whether or not individual species are valid and genuinely different and the issues caused by different species concepts.

However, the recent post on the problem with undiagnostic types masks a more serious issue. Even the best type specimen and a good solid description and diagnosis is often only the start of a species’ taxonomic identity and work for the taxonomist. Taxonomy never really stops.

We’ll keep things overly simple but imagine we find a new species of a brand new mammalian family. It’s some kind of carnivoran with blue fur and giant fangs. That makes it nice and easy to diagnose – blue, big fangs. Then another new species turns up with is also blue and has no fangs, each is clearly different. But what happens now if we get a light blue one with no fangs and a darker blue one with fangs. These are still different, but our original definitions need to shift to take this new information into account. We can’t just go with ‘blue’ but need ‘light blue’ and ‘medium blue’ and ‘dark blue’. So not only do we need to be careful with the descriptions of our new species, but we also have to revise the definition of the original ones too. So even if they are valid taxa and have good descriptions and types, our definitions need to be corrected in the light of new information. Discovery of alternate colour morphs, tooth variation, other new species etc. will only add the need for more refinements.

And this is why taxonomy never stops. All that new information from ontogeny, variation, new analyses (DNA, interbreeding, behaviour etc.) will help to redefine and refine a species’ identity, and new discoveries of new taxa will complicate this further. All of this must be weaved together correctly and that takes time, skill and a good understanding of the situation. Some surprisingly famous species have poor or out of date or problematic definitions and these only get more complicated as time goes on. Calling something Linheraptor or Limusaurus and everyone agreeing it is new is really the start, not the end.

Sinopterus at the IVPP

The blog has been quiet the last couple of days because I’ve been in transit / in jetlag for the last few days as I’m back in Beijing. However, I’m now more or less compus mentus and I have some nice new photos of various specimens from the exhibition halls so the posts will be picking up again and with some nice looking stuff. Stay tuned and in the meantime, enjoy the skull of the holotype of Sinopterus.

Introducing Brontomerus

This is really just a quick post because all the action is of course going down at SV-POW. Yes there is a new sauropod on the block and the SV-POW boys, or at least Mike Taylor and Matt Wedel, are in part responsible. So inevitably you can get all the real details there and I am in this case, little more than the messenger.

Still, it’s always nice to talk about a new taxon and I’m sure this guy, named Brontomerus, will be in the news and blogosphere if only for the name. It shares a large part, rather obviously, with the defunct ‘Brontosaurus’ and that I’m sure will go down well. But this is not a thunder-lizard, but a thunder-thighs. Yes, them named it for having, for want of a better phrase, fat legs. It has more going for it than that of course but for the real skinny, hop on over there and take a gander at the first of what could be quite a long series of posts. And watch out for the inevitable avalanche of inaccurate references to Brontosaurus in the media.

Brontomerus life reconstruction. Courtesy of F. Gascó.

Darren Tanke’s Gorgosaurus preparation: final roundup

I have been less than brilliant at cross-linking all the various Gorgosaurus posts that have been running now since December and finished yesterday with Darren’s final summary and update. It seemed sensible then to have a final little round-up on here back linking to all the previous posts and giving a central repository for everything up to this point.

I also want to use the opportunity to repost a few of my favourite images from the series which are scattered in below. Of course I also want to give huge thanks to Darren for all his work on this. I’d originally conceived of the series of being little more than some nice pictures shows the rock slowly clearing to reveal the underlying dinosaur with a few notes on what was going on. Darren obviously has gone way beyond this with a huge series of detailed posts and documenting every step of the process and every little trick and tip he has going. My thanks too, to the Royal Tyrell Museum for letting us do all of this and stick this, as yet undescribed, specimen all over the web.

Right, here we go:

Continue reading ‘Darren Tanke’s Gorgosaurus preparation: final roundup’

Darren Tanke’s Gorgosaurus preparation 21: The end

The Gorgosaurus preparation on this side is now completed. On February 18th, Dr. Philip J. Currie came to examine the specimen and do some research on it. He will likely return and do more once the specimen is flipped over.

The specimen has now acquired a Dinosaur Provincial Park quarry number: the quarry site is now known as quarry 257. The only thing that needs to be done on the Gorgosaurus block now is the addition of a thicker, penetrating glue into all the rock surrounding the bones so it resists the deep penetration of the curing silicone molding compound and hold together when the mold is removed. This gluing will be done on February 22nd and will then be left for a week or so to fully dry while I am engaged in some other work. This means the rock will now be harder on the other side, but recall the glue is acetone-based so I can just use pure acetone to soften the glue as required. Even though the main block is done (on this side), there are still some small blocks that were removed during the initial fieldwork in 2009. These consisted of two blocks, one an epipterygoid (a palate bone) and a long mid-dorsal rib, with another unidentified bone alongside. The epipterygoid (opened jacked shown above)was started today and went quickly. It will be fully prepared out of the rock. A crew was working near the quarry in 2010 and when they revisited the site, they found another bone being exposed by erosion.

Normally we dig 1 metre past the last bone and stop there. This bone was a little beyond that and it was missed, so was collected in 2010. I worked on that bone as well and see now it is an angular- one of the lower jaw bones positioned at mid-length along the bottom edge. It is good to have these skull bones but they tell us the skull will not be as complete on the other (upper) side as the side (bottom) we have been watching on this blog.


Next updates will cover the molding process. I don’t know when this will start as some other Tyrrell staff do that work and they are (or soon will be) experimenting with the silicone rubber that will soon mold the Gorgosaurus.

Dave writes: This is however, the end of the *preparation* series (hence the title) so we are rather drawing a line under this piece given that every practical part of the preparation has now been done and with Phil’s arrival the research phase of this specimen is beginning. While we will add more during he casting process, this is the end for now. We hope you have enjoyed this and any feedback on the series as a whole is most welcome. Thanks!

All photos here and in the series are owned by Darren Tanke and the Royal Tyrrell Museum.

How complete is complete?

Descriptions of fossils generally include an opening line that comments on how complete the specimen is based on how much material is present. Statements like complete / nearly complete / mostly complete / some elements preserved etc. are all common. These are of course reasonable guesstimates based on what is there, in terms of the total numbers of bones that are present.

However, reasonable though this is, it is of course possible to have very significant numbers of bones of the skeleton be missing and still have an effectively complete specimen. Or to be more precise, to have all of the necessary anatomical information. After all, assuming you have one complete and articulated arm, the other one won’t actually tell you anything you don’t already know (even if it does make for a nicer specimen). You don’t therefore really need one hand and arm or leg and foot or for that matter half the pelvis or shoulder girdle. You can get rid of half the ribs and gastralia and, in theory at least, half of the skull too. In fact given that in most taxa the ribs, gastralia and chevrons are pretty uniform you could loose most of them without compromising any information.

I reckon you could easily loose about 30% of the bones and write as full and accurate description as if you had 100%. Obviously this is just a thought experiment, but it (might) show that a ‘nearly complete’ specimen that’s missing the skull, or both feet might not actually have as much information as an ‘only partially complete’ specimen.

Pterosaurs hanging around

It used to be very common to see images of pterosaurs having from branches or cliffs with their toes rather like some kind of reptilian bat and this was, for a while, considered plausible or even likely in the literature. It also made it into the original Jurassic Park novel showing a remarkable degree of persistence. However, this has (just about) finally died out and for two rather good reasons. This is, hopefully, a pretty simple example of basic comparative / functional anatomy which is very useful for inferring behaviours and the habits of extinct animals.

Animals that do hang upside down by their hands and feet are few and far between. The two obvious candidates are of course the bats, but also sloths. Both of these share a couple of features in common with their anatomy which are clearly distinct from pterosaurs suggesting rather strongly that pterosaurs were not hanging around in this manner.

First off both of these animals have strongly curved and robust claws on their feet (and hands too for sloths) which can hook around object to provide them with the purchase they need. While some pterosaurs do have some rather big foot claws, these are not really in quite the same league as bats and sloths and the vast majority have relatively short claws with little curvature. As an additional point, pterosaurs do have big and curved claws, but these are on the hands, not the feet.

Secondly these animals also have toes that are all remarkably uniform in length unlike almost any other animal I can think of. This of course really spreads out the load of the animal across multiple toes / claws and doesn’t force all the weight onto just one or two and should give them a stronger and more reliable grip. While the fifth toe is huge in rhamphrhynchoids and massively reduced in pterodactyloids, the others are all fully functional and yet are always different lengths to each other, sometimes with quite dramatic differences.

There is then no good reason to think that pterosaurs would, or even could, suspend themselves effectively upside down with any regularity. While I don’t think it’s been mentioned before their plantigrade foot posture might also be an issue. I’m not sure if they could quite straighten then ankle out to be in a straight line with the tibia and if not then this would put a lot of stress on the ankle and make this a difficult pose to hold, it’s not critical but I’d be intrigued to test that at some point.

Exploring and explaining Ask A Biologist

By now I expect all of my regular readers are familiar with my Ask A Biologist site and the general aims of increasing science education and communication to the general public by professional researchers and experts. While this has now been ticking over and doing pretty well (as far as I’m concerned) for four years (wow, that has flown by) it has never really grown substantially. This is a bit annoying but not the end of the world, there are limitations to what you can do on a shoestring and relying on the goodwill and time of your contributors and friends and colleagues. All things considered, I think we’ve done a superb job, even if I am saying so myself on my own blog.

The latest step we have taken is to write up our experiences and the pros and cons of such a site and it’s machinations and we have been able to publish in the recently launched Evolution: Education and Outreach journal. It’s an obvious outlet since they are really all about science communication and bridging the gaps between academic research and teachers (and by extension the classroom)and that is what we are trying to do ourselves.

(As a quick aside, it was very quick and easy to publish here and I thoroughly recommend it. If you have burning sci comms issues you want to get out there and reach a big audience properly, it’s excellent. So get on and do it).

The paper is a short one and tracks the history of the site and what we have learned and experienced through running it. We are a bit unusual in that we are really independent of any university or society and don’t have any formal organisation as such. Things kinda just get done and if things don’t get done, either someone picks up the slack or complains till other people pitch in. This of course means we do have complete freedom to run the site as we see fit and it keeps costs down and stops time getting wasted on meetings and updates etc. On the downside, group apathy can set in and some things really don’t get done if they are never that urgent or that important, and it’s easy for a few of the more active people to dominate proceedings.

Even so, we think this is a successful model for others to follow. The whole site has been set up, run (and undergone a major redesign and facelift) for four years for just over 3000 pounds – that’s an incredible return. We have provided a real service which is slowly becoming more widespread in it’s influence with other sites now making use of our answers as a source of information and more teachers coming to us to help with questions from their pupils and for bits of information for their own lesson plans. We seem to be having the effect we always wanted and that’s a good thing. Hopefully this paper will go a little way to help push that still further and help us reach a still larger audience.

Of course you dear reader can help with that too with a bit of judicious blog posting, linking, mentioning this to your kid’s school, cousins’ science teacher, local nature club, or whatever. We are making a small difference and you can help us make a slightly larger one, so please help if you can.

Hone, D.W.E., Taylor, M.P., Wynick, D., Viscardi, P. & Gostling, N. 2011. Running a Question-and-Answer Website for Science Education: First-Hand Experiences. Evolution: Education and Outreach, in press.

A few more words on distortion

I wrote recently about the ways in which bones can be distorted and modified as fossils when compared to their original shape. And here is an example of that, a Pteranodon metacarpal photographed in the Oxford Museum. Two different things are clearly evident here and perhaps a third.

First off you can see the crushing that has taken place by all the little fragments and breaks along the middle of the bone. In particular there seems to be a crack running the whole length of the midline. Since pterosaur bones are generally hollow then the bone would expect to sort of fold in on itself and crack and break down the middle as it caved in under pressure. This certainly appears to be in evidence.

Secondly the bone seems to have twisted a little. The bone is seen at an angle somewhere between lateral and ventral view, but the condyles (the articulating bits at the ends) don’t seem to quite line up right. This could be supported by the fact that towards the ends, the broken parts are more concentrated in the upper right and lower left part of the bone. This has undergone a bit or torsion along the midline.

Finally, this might have been flattened a bit. Sure it’s crushed, but the shape might still be right, but I’m not sure. Based solely on eyeballing it, this looks wider than it should be for its length. This of course can be checked with a few simple measurements and proportions based on a good and uncrushed specimen, but if I was going to describe this bone that’s something I’d be looking to check.


@Dave_Hone on Twitter

Enter your email address to follow this blog and receive notifications of new posts by email.

Join 355 other followers


Follow

Get every new post delivered to your Inbox.

Join 355 other followers