Posts by David Hone

"Spinosaurus seems the type of bizarre creature that could only be dreamed up by Hollywood."

Not really. In my experience, the natural world is far more creative than human fiction - half the stuff in Avatar is rather obviously modified from extinct animals if you know which to look out for.

I have a couple questions regarding it's depiction in the media:

"1/ It's nasal sensors leed us to believe it was quite aquatic like a crocodile."

It's news to me that anyone has ever said anything about this. What leads us to think it was partially aquatic (note, partially, like an otter or croc, not fully like a dolphin or icthyosaur) is that is does have a very crocodile-shaped snout, and the position of the nostrils are like those of aquatic vertebrates, it's found in environments with lots of fish, and one of it's close relatives, Baryonyx, is preserved with parts of fish in the stomach.

"What evidence do we have that it spent significant time on land?"

Well the fact that it's a biped, and those tend to be primarily terrestrial (or at least more than capable of supporting their weight on land) and it's not built to swim well (no deep tail like a croc or beaver, no reduced limbs to cut drag, or greatly enlarged limbs and feet into paddles, so super dense bones to stop them floating etc.).

"Could its long fingers and toes have been webbed for a very acquatic existence? "

Well they aren't actually that long, but about normal for an animal of that size. They could have been webbed sure, but that wouldn't make them great in water, merely a bit better than other theropods.

"And could its long legs been used for Frog motion in water and Bird/Kangaroo hopping motion on land? (I don't think a full skeleton has been found so are it's limbs, hands and feet assumed from Baryonyx Walkeri?)"

There's no full skeleton no, but Suchomimus is nearly complete. To move the legs like a frog would take a complete rearragemnet of the legs and pelvis, so no. No 10 ton plus animal could hop either, so that's also out.

"2/ What evidence is there for it having a slim, lizard like physique with a skin covered sail along the spine"

Well that's how anuimals are built. They don't tend to have much mass outside the ribcage or packed over the backbone (camels are the exception not the rule).

" (are there any other animals other than Dimetrodon with such a spine?).:

Lots. Not jsut close relatives of Dimorphodon like Edaphrosaurus, but dinosaurs like Beckelespinax, Ouranosaurus and Dicraeosaurus.

" If it were a warm blood dinosaur, would it need a decent amount of insulation (fat/feather as per a penguin)"

It depends how active it was, waht the temperature was typically like, what water or shade was available etc. Hard to say, but based on the other large theropods, very probably not.

" if acquatic, whereas a cold blooded crocodile does not? Could Spinosaurus have been fat like a cetacean with skeleton bearing little resemblance to a larger physique?"

Nope, see above on ribs. And physiology / temperature is way, way more complex than just "hot" or "cold" blooded.

"The reconstructions of Spinosaurus seems to have started with a hypothesis of a crocodile;"

No, it's based on lots of good evidence: comparative anatomy, diet, isotope analysis and taphonomy among others.

" but could Spinosaurus have been more like a cross between a penguin, a frog and a manatee?"

Sorry but no, absolutely not in any way at all.

I think you're thinking that a species originates with just one or two new individuals, but that's really not how it works. If that were the case, then yes, inbreeding would be a huge problem. However, species don't jsut pop up like this, whole populations or lineages slowly becomes different enough to their relatives that we define them as separate species. But that may have occurred over thousands of generations and may involve a popualtion of thousands or even millions of individuals, so there's naturally a wealth of genetic variety there.

Are you really sure it's the same one? They do kinda look alike. :)

I'm sure it's not normal, but not impossible. They are smart birds and food can be hard to come by. With the right winds a 100 mile journey is not necessarily a huge effort for them, so the trade off between the trip and what it might get out of it (more food from you) could be worth it.

There was an abstract from a conference some years ago on this describing ceratopsian skin referred to Triceratops with distinct nipple-like shapes on some sclaes, which implied something else came off from them. Coupled with the filaments seen on Psittacosaurus, this was presented as evidence for some bristles being on these animals. I'm not wholly convinced and much more importantly, to my knowldge, this has yet to be properly published / described. It's certainly plausible, but I was to see a formal, perr-reviewed description and comparison to other specimens and that has yet to appear.

There's nothing specific for Pteranodon in the sense that there are no fossils of it directly preserved with fuzz (aka pycnofibers). However, this is only very rarely preserved, so our record o fit in pterosaurs is currently very limited. We do though see it in some of the most basal pterosaurs (anurognathids) and other basal forms as well as a couple of basal pterodactyloids. That's about it for now, but of course the more material we find, the more likely we are to turn up specimens.

I, and I think for other pterosaur researchers, would say that it's more likely than not that most if not all pterosaurs had pycnofibers. Pterosaurs were actively flying animals and regardless of their physiology, would be interested in retaining heat, and some kind of fiber covering would do that. Given how early this eveolves and that it's retained in a variety of forms for at least 100 mya, it would seem most odd if other pterosaurs didn't have it.

I think you've been taking Jurassic park a bit too literally. It was a work of fiction - there's no evidence they were a fraction as intelligent as portrayed on the screen. Even if they were, yes there are a number of animals (some dolphins, New Caledonian crows, apes) that are extremely intelligent. As for the noises, well those were special effects, and based on living animals: there's traces of sealions and alliogators in there if you listen close.

I always liked Bill Hicks' response "You know it took more effort to tell me that than to leave me alone?". :)

I knew I'd seen soemthing on this. Here's an essay on the subject by occasional AAB contributor Dr Darren Naish: http://scienceblogs.com/tetrapodzoology … pressions/

I really can't add any more than this, so hopefully it'll answer your questions.

I can't see them recognising themselves at any level. Recognition in a mirror is a recognition of self, but even if the clone, looked and smelled and acted identically to stimuli, it's still a different individual organism. Why would you recognise it as 'yourself' any more than you would an identical twin?

I have e-mailed Manabu and hoped he'd be around to tackle this, but as he's not, I'll have a go.

Spinosaurs have long jaws and in general this correalted with a low bite force (it's simple mechanics, it's hard to put pressure on something a long way away) and they don't have huge areas of muscle attachments at the back of the skull. Collectively then, they probably had (for their size) a pretty weak bite. I would not expect even a huge spinosaur to have a bite nearly as strong and a large tyrannosaur.

Hi Pat,

as someonme who did his PhD on pterosaur origins, you may have come to the right place.

The shprt version is that we really don't have a good idea of the origins of pterosaurs and their transition to flight. We have some ideas and there is work on this but not much, mostly becuase the fossils are very scarce. On average the smaller an animal is, the less likely it'll become a fossil, the older it is the less likely it'll become a fossil, the more fraile it is the less likely it'll be a fossil, the rareer it is the less likely it'll become a fossil, and the further from water (well you get the picture).

The first ptersoarus lived a long time ago, were small, probably few in number, fragile (hollow bones) and living in trees. It should be no suprise really that actually the fossil record of the earliest pterosaurs is pretty terrible. In fact I'd say it's better than we might think.

However, this is a typical creationist tactic and a pretty pointless one. If they want to show evoluton doesn't can't work, it's obviously unfair to pick on an example where we don't and can't know much. Surely if evolution were false and creationism correct, they would be able to simply disprove any proposed evolutionary transitions in the fossil record? Why did they not pick on the origins of birds where we have thousands of specimnes from dozens of species showing grliding and prachuting transition formas, the changes in feathers, wing shape, shoulder joints, tail anatomy, brain shape etc. etc.?

To pick a (possibly poor) analogy - it's like saying you can't say that car X was built from blueprints by picking a car for which you don't have the designs available. But then applying that same argument to all cars, even if you have all the blueprints and plans and design notes.

Sure, there's tons and tons of species where we don't have a good fossil record, or simply haven't researched on them much. But that's hardly a fair test. They can't attack the good examples that clearly demonstrate the principle with superb evidence, so attack those which we admit are lacking data and claim that also affect those that are better supported? Right.

As I say though, we do have some ideas. We have a good idea of pterosaur wing structure and that suggests early forms had a very broad wing which would link to a gliuding origin. It also looks like early forms were arboreal, again fitting this model, and so we can at least being to put together a plausible hypothesis about this.

You have to realise that we have only about 10 good Tyrannosaurus skeletons of a population that could have been in the tens of thousands and around for millions of years. The odds we have a good idea of the largest animal is pretty remote. God and pick 10 random lions today and the odds you have the largest lion ever (or even close to it) are basically nil.

So could Tyrannosaurus have reached 14 m or 15 m, very probably, 16 or 18, even 20? It's far from impossible. But of course picking out true giants can give you a poor impression of what these things were really like there might have been a single Tyrannosaurus that was bigger than every other theropod ever, but if 99% of them were smaller than an averaged sized Giganotosaurus say, it's not really right to say T. rex was bigger.

It's also worth noing that lenght can be pretty misleading. Add a huge tail to an animal and it wouldn't be much heavier bout could be twice as long - Diplodocus is about the same length as Brachiosaurus, but weighted probably less than half as much: would you really call them the same size?

Based on waht we know, there's half a dozen contendors for 'largest' theropod, Spinosaurus, Giganotosaurs, Mapusaurus, Tyrannosaurus and Carcharodontosaurus and probaly a few others like Tarbosaurus and Zhuchengtyrannus were in the same ballpark. Which was on avergae the longest / heaviest, we really don't know, most are know from far too little remains. But all were truly massive.

I think a good few would do quite well. Things like whales have bounced back quite effectively as soon as hunting stopped so there;s no reason tot hink that if we aleviated various human pressuresd on them they wouldn't continue to improve. As David says, others might be byond the point of no return (not that they cannot be saved, but that it would requite human intervention to save them, so without us helping they might be doomed). Things like Sumatran rhinos are so rare and so scattered that a single disease or bad year with a few accidents might leave them with only a few animals so far apaprt they wouldn't be able to find each other and breed.

On balance I think an awful lot would do pretty well, but sadly not all.

There's also quite probably an age component. Evolution will select most strongly for things that affect reproduction and child rearing. While obviously there are cancers that affect children and young adults, once you hit middle age, you have grown up and generally had and raised your kids. A cancer hitting them doesn't affect reprodcution or passing on genes and while obviously horrible for the individual, doesn't really affect things in the long run. Hence there's no evolutionary pressure to evolve greater resistance.

Eeek! Well there are a few things out there, people have welded together some big trees and while you cant use it as a single diagram (if that's what you want), I would try the Tree of Life website. You can click your way through that and it covers huge numbers of species living and dead.

It's certainly a crab I'd hate to try and say what species but the leg shape and position of the joints are right for a crab and wrong for a spider. Most obviously, it's got no visible abdomen which is pretty much essential for any spider and normal for any crab (in crabs they are present, but folded back under the body).

Yeah, that's pretty much it. When they talk about relatedness at the local level (sibling, parents and offspring etc.) they are talking about only the bits on top of everything else that you do indeed share with a vast number of organisms. It's only a couple of % of your DNA that 'makes' you human so to speak, so yeah, it's that bit that you can be 50% realyed or 3/4 realated as we are indeed about 98% chimp and so on already.

That's interesting, and yeah, 7% is not really a lot by any measure, even if more go towards it later in life, that's a pretty small fraction.

The first one is a museum catalogue number, the second a nickname of a famous specimen and I assume the third is, but I've not heard of it.

I didn't know that etymology of that, cool stuff Dan.

You are right that to an extent 'jungle' overlaps with 'rainforest' to a degree, but I'd call the former a subset of the latter. I was taught that jungle is really just a term for especially thick plant growth at ground level. When a big tree comes down and lets the light in, or around the edge of water, you get huge tangles of short plants and this is jungle. So you get jungle in a rainforest.

As such, really the question could be more boiled down to, do you get lions in rainforests and yes you do, in both Africa and as you say, India.

Certainly. While we normally think of lions as living in a pride, it's quite normal for males to live on their own or just with a brother or two. Young males that have not yet taken over a pride or old ones that have been forced out generally live alone and are typically called 'nomads'.

Ok, I'm totally wrong, they really are very much immune to rattlesnakes and related forms. Wow. Cool!

No idea about the Asutralian lot though....

Yeah, it's not the kind of thing you can calculate odds for. I'd simply work under the assumption that if they're there, they'll turn up sooner or later. :)