These animals are extremely simialr (and are certainly very close relatives) and so some palaeontologists think they should be considered the same genus, whereas others are happy that they are dstinct and separate. When animals are this simialr, opinion can be split, so you can take it either way. Personally I think they're probably distinct.

Maryam has written back to say she found a good book on this subject before we could get to her question. She recommends "From Genes to Genomes: Concepts and Applications of DNA Technology".

(posted in Fossils)


that's far from an easy question. Your numbers certainly sound about right, but I'd stuggle to confirm them.

I'd suggest the the PalaeobiologyDatabase. That indexes literlaly tens of thousands of fossils and where they have been found. Don't forget, some small museums have hundreds oif thousands of specimens and these are spread all around the world, the information age has not caught up and there is no single index of even small groups like dinosaurs.

In answer to the first  part of your question is 'probably not'. The earlier dinosaurs with feathers we do have tend to have down-like fluff (as in chicks) and don't have quills without the 'feathery bits' on them, so a bird with just quills is quite different to what we see. In addition, those areas not covered by feathers in dinosaurs were probably still covered with scales unlike your chickens.

As for the locmotion question, the best thing I can do by far is point you to this piece written by a colleaue of mine on this very subject and he knows it a lot better than almost anyone else: … o-the-walk

Hope that helps,


As far as I'm aware Ankylosaurus is the largest of the ankylosaurs. There are a couple that are similalrly sized, but it's the largest one that we have many good examples of for sure.


this is indeed the ischium and it mostly operates in anchoring some of the muscles that help to move the legs backwards (and thus pus the animal forwards). In some dinosaurs (like Tyrannosaurus) the ischium is actually pretty small and flimsy and is probably doing not much more than supporting some of the internal organs in the body, with more of the muslces here anchoring on the base of the tail.

Hope this helps,


(posted in Birds)

do blue tits avoid a nest box placed near a honey suckle plant ?

There are some videos online of large eagles basically knocking sheep off of cliffs (grabbing them with their feet and then flapping hard to pull them off the edge) and then flying down to feed, but here they are animals already on the edge of cliffs or on steep and narrow rocky slopes (not the kind of places humans generally hang around on) and plenty of people weight more than a sheep and would have their arms they can try to fight off such an attack. As such, while it's just about possible, as noted above I'd be amazed if they even tried it (summing unaware people were standing on cliff edges with nowhere to go) and then they would likely give up as people were too heavy and fought back too much.

(posted in Birds)

They have basically trimmed their wings so that they are gaining lift from the air moving over them, but also effectively falling forwards under gravity (not quite enough lift!) so are going forwards. A good flap will make a big difference too.

I think it's a tooth (probably from some large mammal, I'd guess a molar of something like a horse) that has been really badly worn by being in the sea. The end on the left of the last picture looks just like the wear surface of a grazing mammal that has jsut had all the texture worn off leaving the very base and the root of the tooth.

Take a look at this pic for example. Plit the tooth in half and wear away the bit at the front and you'd have something pretty simialr to what is in your photos: … 571502.jpg

(posted in Evolution)

OK so there's a whole bunch of things here - first off thechnically there were no marine dinosaurs - there were a bunch of large marine reptiles like plesiosaurs around but these were not dinosaurs. Secondly, not all the dinosaurs were wiped out - the birds survived!

There's a whole raft of factors that influence survival from a mass extinction (like the meteor impact) the include body size, reproductive rate, ability to move to new environments, where you live etc. etc. (there's a review I wrote here: … s-fossils)

This expalins a lot of who survived and who didn't for the big impact, but there's some unexplained bits like why the crocodiles sneaked through when generally they did pretty badly, why some bird lineages survived and o0thers died (including various small dinosaurs) and some simialr issues.

Certainly natural selection was Darwin's foudning concept on which evolutionary theory was built. Now we do generally expand it to include sexual selection (also something Darwin worked out) and things like genetic drift. Modern definitions of evolution encompass these and some other areas, but it's also true that natural selection is to a degree first and foremost of these.

(posted in Birds)

I'm afriad this will be all but impossible to work out - lots of birds will fly at night if disturbed and if you were driving a car that could do it. The eyes of manyu animals (birds and bats) will glow slightly red in a bright light as this is the light reflecting off blood vessels in the eyes.

So unless you have a good idea of the size. shape of the bird, any colours, behaviours etc. I don't think we can even begin to guess!

The obvious one is Steve Brusatte's 'Dinosaur Palaeobiology' or perhaps the 'Complete Dinosaur'. Both are quite technical, but might be what you are looking for.

As correctly spotted by reader 'Paul', this is probably a sternum (breastbone) from a gull.

(posted in Birds)

This alternative answer has been sent in by
Coilin MacLochlainn, Editor, Wings magazine, BirdWatch Ireland:

A Blue Tit has taken up residence in one of several Schwegler nestboxes I 
have on my house and has been going in and out for about two weeks now, from 
April 7th 2015. It has been banging away on the inside of the box the whole 
time, like a tiny woodpecker. It took me a while to figure out that it was 
the Blue Tit making this strange noise. At first I thought it was trying to 
fashion the inside of the box for its nest, as a tit in a tree-hole might do, 
or as woodpeckers do. But Schwegler boxes are not made of wood, and Blue Tits 
are not able to tear small strips off them or make any impression on the 
inside surface.

Every day, the Blue Tit bangs away in the box, goes away for a while, sings 
loudly from a tree and then returns to continue banging; this goes on all 
morning. It struck me that what it was up to was trying to attract a female 
to pair with him and occupy the nest. His rhythmic banging not only drew 
attention to the nestbox and to his territory, but also to his strength and 

We've had an e-mail to the site from someone called Paul who has identified this moth. He writes:

It is called an   Indian grain moth a.k.a Indian meal moth. I don't know if they are in 
England,but I'm in America and they are common pests here. They were imported 
from India.They like flour and birdseed,among other things. There is a wikipedia page about them and how to control them.

Yeah, I actually had access to the key specimen when the original paper came out and have a very hard time to accept any of the claims made about it with regard to venom-delivery-like anatomy. It's like al;most any other theropod in almost every major regard, so I'm sure there's no good evidence for a toxic bite in this animal.

It has certainly been argued that humans in particualr are some kind of 'inevitablity' but I, and I think the vast majority of biologists, don't buy it (and this argument is generally put in some kind of religous, rather than scientific, context).

It is of course hard to say quite how likely, or unlikely, certain events are when the only real datapoint we have is ourselves. Certainly highly intelligent animals have evolved multiple times (both crows and parrots have appeared entirely independelty of one another, and arguably elephants, various dolphins and octopus could be put into a simialr category) suggesting that various different evolutionary pressures can produce simialr results. Whether or not any of these animals are truly sentient is very hard to say and this is an area where there has been a huge amount of research recently.

Given this, I can imagine that given enough time one might eventually see one animal eventually arise (essentially playing the odds with as much time as possible) that would fit the bill, but it's obviously very hard to say.

Hi there,

great question! The reason such marks are generally considered to be from cannibalism is that bites from a fight would probably show evidence of healing. We can see how bones heal after injuries so bites marks on bones with no healing either occured right before, or any time after death. At least some of these also occur in places that would be pretty hard to do during a fight (on the tips of toes, back inside the jaws) and so were probably inflicted on an animal after death, and thus during feeding.

As a result, it's probably safe to infer (for some, mostly we canoot do this) that they were indeed both feeding traces and makrs left by the same species, and sop can infer canibalism.

That is probably accurate. We don't know of any animals or plants currently that exceed these for mass, though some got fairly close. It's not impossible we will find evidence of larger but extinct species in the future, but at the moment thus is correct.


well first off 'pterodactyl' is a sort of duff name, it is extemely common, even ubiquitous, but the correct term for these animals is 'pterosaur'.

As to actually answering your question, the best source I can reccomend is, a site I helped develop with a number of colleagues all of whom are researchers working on these animals. There's a whole bunch of information there, but if you look to the section on anatomy ( this should really help out with all the details. Scott Hartman's 'Skeletal Drawing' website also has soem highly accurate reconstructions of the famous Pteranodon which should help.

There's really nothing I can really say about this. A quick search reveals no papers or even photos of the specimen so I really can't comment on something I can't see that has no real description.

(posted in General Biology)

I think the question is "Could we duplicate a zygote at an early stage after fertilisation, and then keep it in storage and use it to develop replacement organs for the person later on".

If so, I think the answer is basically: a) not with current technology, and b) there would be some major ethical issues about it.

This is one of those areas where really it is impossible to know. On the one hand we can get a vague idea of how smart an animal is by comparing the size of its brain to the size of the the animal, and in the case of most dinosaurse they don't come out well. Still, some very complex behaviours are possible with a small (absolute or proportional) brain and I wouldn't rule out that they could perform simple tasks or solve simple problems, but it would be impossible to know and the evidence if extremely limited.

Well 'accurate' to me kind of implies it is something that would happen, but it is accurate in the sense that this is at least a viable possibility. We know this kind of thing happens in various animals (indeed, it's been strongly suggested to be a key part of the origins of birds), and many dinosaurs were reproductively active before fully adult in age / size so tyrannosaurs would be credible candidates of a group where this could occur.

The real question would be *why* would this happen - things don't spontaneously change in this way, so there would need to be a strong selective pressure towards smaller size or reproduction at a younger age or something simialr.

(posted in Birds)

Birds do often have long feathers on their lower legs. Thanks to the way birds stand their thights are rarely seen and most of what you see is the lower leg and then the long bones of the foot (this is why they often appear to have 'backwards knees', it's not the knee but the ankle) before the toes spread at the bottom. If you watch soemthing like an eagle about to strike with the legs hanging below the body then those long feathers are indeed anchored on the lower legs and not jsut extensions of the body. Only the feet are 'bald' though even those often have some super-fine and small feathers from between the scales.

I have to say I'm really not sure what that is as the photos are rather low resolution. It does look like a chunk of jaw with some teeth in but I strongly suspect it's simply a rock that looks a lot like a fossil rather than a genuine one (this is actually really common). With some batter images I might be able to tell, but I don't think this is bone.

As Mike notes, we're basically hampered by a lack of data. There are too few species where we have a) lots of good skeletons, and b) that are from roughly the same time and place and have a range of sizes and ideally ages. Some analyses have suggested dimoprhism is present, but the data is often limited and the strength of the results very weak - arguably Protoceratops is the only good candidate at the moment, though I'm actually working on revising this and some others at the moment, so stay tuned!

Ok yeah, I got that wrong, but the conceptal point is still valid even if I strayed a bit with the values.

OK yes, that is really big for a human, but the point is it's still not hitting the peaks of humanity (again, leaving outside for example people with excessive growth hormones) and that you really can't pick one value as some 'norm' for a species and a range, even a really big range, is pretty common.

Sorry for the enormous delay in replying, I thought I'd actually answered this but must have forgotten!

Our best assumption is that basal tyrannosaurs were floating around from the Upper Jurassic onwards in North America, but as they were likely small and rare, their fossils are scattered or remain undiscovered. Occasional finds like Stokesosaurus do suggest they hung about but only flourished in the Late Cretaceous.

Yep bryan, that's pretty much it, we've known about there being *something* there for a good long time, but it took a specimen as good as Sordes to give a decent idea what it was. While this does immediately provide an inference that these were widespread, based on only a couple of datapoints it was tricky to know. Only more recently (the last 10 years especially) have we had multiple specimens of multiple species covering many major clades of pterosaurs hat strognly suggests that pycnofibers were at least the default and likely covered part of most, if not all, pterosaurs.

Well Mike I don't see any obvious adaptations to really tearting up / into things (no hooked beak for example) and while they could have probably taken chunks off bigger things at a push, they are buiklt with a stork-like apparatus and that would imply they would tend not to break-up what they ate.


I'm not going to answer all of these as there's a ton there and as you'll see below, picking up on these kinds of details is basically meaningless when talking about a single value.

As David notes, most dinosaur specimens are incomplete, often very incomplete (there is not that much of Carnotaurus for example), and even complete animals may be juveniles etc. Also of course a single value at all is not very informative - humans are not 1.70 m tall, but antyhing from 1.5 to 2.5 and that is before taking into account exceptional individuals or medical conditions like growth hormone problems. To pick a single value for a dinosaur genus as its size (be it height or length, and the latter is extremely varibale thanks to their tails) does not really tell you very much.

In terms of weight, this can be estimated by a number of ways, but essentially it all comes down to trying to put back all the muscles and organs on top of the skeleton. This can give very different numbers becuase in addition to the variations above, don't forget than animals can change a lot - bears can lose about 50% of their weight during hibernation, and can easily be anything from 150-200 kg over the course of a year so saying 'Tyrannosaurus was 6 tons' is not very informative. Even 'this individual of Tyrannosaurus was 6 tons' is not much better when it might have easily varied by a ton either way across a year, and then there's the errors we might make getting to the number 6 in the first place.

We can do all of this actually pretty well overall, but we need to think in terms of ranges and avergaes than single numbers.

Well an expandable throat probably would not help much as the kaws (unlike those of a pelican for example) are basically rigid. The limiting factor of swallowing is thus probably going to be the back of the jaws and not the throat. We don't have any complete skulls for the big azhdarchids, but I'd guess it was not much more than about 30 cm or so across, to still pretty small given how huge they were.

Well there's not much of it and what is known most people consider to be a tyrannosaur of some kind. It's not always easy to ID specimnes based off of limited material, but that may be all we have. Other specimens might turn up of Bagaraatan, or we might get more data from other things that show an affinitiy to it, but there's jsut not much material.


It's actually almost impossible to ID dinosaur eggs unless they are in a nest or associated with an adult / embryo. There is a huge amount if variation in the egg shell structure and the size and shape, and even closely related species can have very different eggs and very different species can have simialr eggs. In short, this is (unless it's a fake, and there are some incredible fakes on the market) almost certainly a dinosaur egg, but there's no why to ID it.

I'd also add that based on the colour and preservation, it's very probably from China and might well have been illegally excavated and exported (China has really strict rules of vertebrate fossils) so do look at where specimens come from and support ethical collecting.



(posted in Birds)

This question really is no different from your last one on dinosaurs - sure it's *plausible* that given enough time major changes like shifts from herbivors to carnivory, flight to flightlessness and especially increase in size could occur. It has happened multiple time in multiple lineages (look how many times animals have goen from the water to land and then back again later for example). Working out which might do what in the future however is increidbly hard since it is hard to predict what a specific lineage will do even if we can often sayn on average what is likely to happen or what is possible.

Well it's obviously speculative, but I think the short answer would be 'unlikely but not impossible'. It's quite common for carnivorous lineages to shift to herbivory, but the reverse is rather more rare and the ornithopods were very specialised as herbivores - even with the theropods taken out, there would have been other lineages well placed to fill the carnivorous niches (like crocs and the like) that would be in a position to move in as it were.

Still, pretty much all animals are to a degree omnivorous and I have little doubt at least some things like hadrosaurs sucked up the odd meaty meal deliberately (in addition of course to eating things like insects on the leaves they consumed) and one can easily imagine that the animals who tended to do that might rapidly become better at it in the absence of serious competition and then selection would soon kick in and this could ramp up quickly.

Well genetic drift is also random and can lead to fixation of essentially randomlyselected genes leading to a change in the population / species. So some elements of evolution can be random, but that is very different (as noted above) to saying that evolution as a whole is random, selection is random, or that various features / changes have come about rnadomly.

That looks very much like just a lump of some odd mineral to me I'm afraid. Soft tissues do petrify, but usually they are pretty touch materials (like skin, claws, feathers) and very rarely do things like muscles even partly preserve and then they are generally quite shrunken and damaged. Eyes basically never preserve except under very special circumstances and exceptional preservation conditions and even then as little more than a stain on the rock. I can't conceive that an eyeball would fossilise like this wthout the entire skeleton and every major organ (heart, lungs etc.) also surviving in immacualte condition.

Pretty much all large terrestrial animals (birds, mammals, reptiles) can swim to some degree. They generally all float since thanks to their lungs they are less dense than water, and then some combination of arms / legs / tail will propel them through the water.

As a result, I'd expect these dnosaurs to be able to swim reasonably well. They have powerful legs and a strong tail, and should float pretty well. Sure, things like crocs that are well adapted to life in water would be much better, but they should be fine in water and able to move around relatively freely compared to many.


well this is one of those areas where it's obviously hard to say. This is very much a credible candidate - it's a really, really big predatory shark. However, we don't have that much of it (little more than teeth and some vertebrae) so getting an exact size is hard (and certainly some of the numbers associated with it are pure exaggeration) but also how exactly do you define 'macrophagous'? Generally that's something that eats large things, and so rules out filter feeders like the blue whale, but I'd still suspect that the sperm whales around now (and indeed in the fossil record) would be bigger (heavier) than the bigger C. megalodon, and are very much macrophagous.

So not much in it, and these animals were certainly impressive and large predators, but working out exactly what was the largest when is not really very relevant to biology or palaeontology, even if it can be fun.

(posted in Fossils)

Looks quite a bit like a vertebrae from a whale or dolphin, though I'm not great with these kinds of bits.

(posted in Fossils)

There is not really a palaeontology undergraduate course available in the UK. Palaeontologists generally come through a bakcground of zoology/ biology, or geology and then begin to specialise at the Masters level. There are some joint honours programs or MSci courses that allow you to do large chunks of both biology and geology modules, but this is about as close as you can get normally. The real work comes after the first degree, but to get there, as David notes, you need to be strong in the sciences.

I'm pretty sure that is a shell of some description. It looks familiar but annoyingly I can't quite place the name right now. It would likely be something close to barnacles.

(posted in Fossils)

It looks mammalian, but it's ery badly worn. You have little more here than a centrum and while I can rule out a couple of things based on the approximate size and the fact that it's relatively long, I can't offer much more than 'probable mammal, not that small'.

I think what you have proposed is certainly viable, but I'm not awae of any evidence to support it and it's probably largely untestable with the current data. It is plausible that early archosaurs did have some kind of cover (remember, its present in both early pterosaurs and various early dinosaurs - like endotermy / raised metabolism, it could have appeared before this point) which would then be an issue. However, the whole thing may be chance - obviously this is a very unsatisfactory explanation, but when you are talking about only a couple of lineages (if for a long time) then it is possible they simply never had the option to srink, or were in an evolutionary selective environment that encouraged larger size for more active animals. After all, mammals and their ancestros are endotherms and have done very well at small size - perhaps they simply got in first to the small niches and the archosaurs never competed effectively at small size and so stayed large.


that's a tricky question as it depends a lot on what you want to do and how big your model is going to be! If you want it to actually fly and change shape like a pterosaur wing, then things get very complicated very fast, and you may want to simply use something like a nylon sheet (essentially the wing from a kite) under tension.

For a static model (i.e. one to go on a shelf or hang from a ceiling) then you have a few more options. For a large model, actually something like fiberglass might do wellk, if the layers are put down right, you can make something that has a nice fibrous texture, but is also thin and stiff. For a small model, a simple sheet of plastic well cut and filed should do the trick.

If none of this looks like working, post a new question with some more details and I'll try to add some more ideas.