(posted in Mammals)

I should add that the term 'lion' is just convenience. The animal is a true marsupial and not related to the cat family at all. IT simply looks like a lion (convergent evolution) as it has a similar body shape, jaw structure and probably a similar mode of life (as a large active hunter). The label of a 'lion' is just there to give people and idea of what the animal looked like - don't fall into the trap of thinking lions somehow became marsupials.

Well, Vincent, we really cannot give out medical advice and of course you do not give us any details. However, I would advise you to see a doctor as soon as possible. You could get all kinds of nasy complications at some point as a result of damage to your bones, nerves, tendons and muscles in your fingers, and leaving it alone won't make it any better.

I should add that although Mike is quite correct - we simply avoid religion as a matter of policy on AAB - ID has been shown to be a form of creationism both in the legal courts and by admission of many important ID proponents.

It has no scientific value as it presents no theories, no analysis, no research and no evidence.

Science is the testing and analysis of natural phenomena using natural laws and explanations. As a result, the existance (or not) of any god is irrelevant as by definition it is supernatural and thus outside the laws of nature and science. To suggest otherwise is simply unscientific.

Well Tom, there can be practical applications to evolution. I know of one study that used the traits of mutation and descent in applied engineering. A company wanted to design a better nozzle for a pipe outlet and took a normal model and had it cast 10 times is a plastic that was then deliberately deformed as it was made.

They then took these modified nozzles to see which was the most efficient and made more copies (again with deformities). After a few generations of this they had created a nozzle about three times (if I remember correctly) more efficient than the original. In a classic copy of evolution, the best adapted (here most efficient) were selected for, and the lest adapted were removed. Errors in repliction (the casting process) occasionally made better nozzels and these were then used for the next moulds (had the most descendants).

Of course, we also use evolutionary theory for all kinds of medical applictions - you need a new 'flu injection every year (as do your pets for various other viruses) as these are constantly evolving and we need to beat them. If we are ever to halt diseases like AIDS, malaria, and many cancers we have to understand how and why things evolve.

The various plates and frills on many dinosaurs are a bit of a puzzle to be honest. We have several ideas for what each may have been used for, but chosing between them with only limited evidence is very difficult.

The plates on the back of Stegosaurus had a large number of grooves along their surface that would have carried blood vessels so it could certainly pump some blood nto the surface of the plates. This may have been to make them more colourful so scare of potential predators as you suggest, but it may also have helped it show off to other stegosaurs during the breeding season (rather like a peacock). Filling the plates with blood and facing across the wind could also have helped keep it cool if the weather was hot. Finally, it has been suggested that Stegosaurus could flatten the plates over its back to give some armoured protection from carnivores. Certainly there are marks to attach muscles at the base of the plates, but these would probably have been too weak to move the plates far, so we can at least rule that out.

Still, the plates may have been used for multiple purposes, to cool off and attract a mate. It is very hard to tell, and perhaps we will never know.

The bony neck frill of Triceratops is also a mystery. All of Triceratops' relatives have frills with large holes in them to make them lighter, by Triceratops had a frill of solid bone! Again, this could have been used to scare off predators, act as armour, or help the animal display to other members of its species. The fact that only Triceratops has a solid frill suggests that other ceratopsians (the name given to its relatives) used their frills mostly for display, but that the frill of Triceratops had a further purpose. Triceratops lived at a time when Tyrannosaurus was alive (unlike other earlier ceratopsians) so had to deal with a larger and more dangerous predator that its relatives so perhaps the frill here also served as armour.

Again, finding the exact use of a feature of an animal that lived tens of millions of years ago is difficult. We can compare the structure to those of animals alive today to get a good idea, but of course something like Stegosaurus simply does not exist now, so we are forced to make reasoned guesses. Still, they are good guesses and based on as much evidence as we can find. Palaeontology can be very exciting as a single discovery can change the way we think about certain animals or features. One day we may find several Triceratops skulls with bitten frills full of broken Tyrannosaurus teeth. That would still not be conclusive proof, but it would swing the argument in favour of the frill acting as armour. Just wait and see......

(posted in Evolution)

Michael,

This one is really tricky to work on. Pretty much by definition evolution takes a long time, however, just how long something may take to eveolve (a certain behaviour, an organ, a new species etc.) is more or less unknown. Some things might evolve and become fixed in a population in tens of generations, while other species may look nearly identical after tens of millions of years.

Dramatic changes to an environment seem to be catalysts for rapid evolution. After all, if all your food goes extinct, the climate changes and you are stranded on an island you will have to evolve fast or die. Species may be unchanged for generations beofre 'suddenly' evolving new traits, though probably nothing quite as dramatic as Stephen J. Gould's 'punctuated equilibrium' model.

Some mutations can be pretty dramatic and operate over very short periods of time (though nothing like the single generations of the X-Men unfortunately). In one recent study of lizards on an island, scientists introduced a new predatory lizard. The prey lizards had always lived on the ground without much threat and so had a variety of leg lengths, reflecting a lack of selection. Now they rapidly evolved much longer legs in order to become faster and escape the predators. (Here the word 'evolved' is a little akward, actually the short legged lizards were eaten - but certainly there was selection from the lizard population). Afterwards, the remaining lizards actually reversed the trend fot long legs and instead evolved short legs which they combined with a new behaviour - they started climbing trees.

Believe it or not, these two turn arounds happened in just a year. First the lizards became longer legged, and then shorter legged (shorter than the originals) while adapting to a new behaviour. Two complete changes in shape, plus a new behaviour as a result of a single new factor in their environment (a new predator). This just goes to show how fast evolution can be. Scale that up a few times and you can see how profound changes can happen very, very fast.

To be picky I would be very surprised if humans evolved in 3.8 years - I imagine you mean 3.8 million. :-)

Still, humans did evolve relatively fast, but they were probably helped by their brains. A large brain allows for more complex social interactions and more complex behaviour (and in our case more tool use). With better survivorship and an increase in ability to hunt with new tools, this may have allowed us to spend more energy growing larger and evolving better brains in a snowball effect.

Some calculations by Richard Dawkins suggested that the eye could evolve in as little as 500 000 years. These were deliberately on the short side, and I doubt anyone would seriously expect that to have happened, but it is certainly possible. If something as complex as an eye can for in half a million years, then humans appearing from advanced apes in nearly 4 million years does not seem so extreme.

Thanks Wade (and Darren)! I knew that would come back to haunt us!

For those who are unaware, our member Darren Naish put out some advertising blurb for us on his blog (the superb Tetrapod Zoology). In it he posed some hypothetical questions that we could answer over here at AAB, including the one above.

This might take a while to answer.....

****UPDATE****

Having sent out some requests I have a (sort of) answer. According to my colleague (and genuine Australian) Dr Adam Yates, live echidnas don't really smell at all. Their only real odour comes from whatever soil they happen to be digging in.  As a result, newly dead echidnas probably don't smell of anything much, but based on his dissections of various marsupials, Adam assures me that they probably wouldn't smell "sweet and fragrant".

Not a great answer I know, but hopefully that is good enough.


My thanks to Adam Yates (currently working on dinosaurs in Johannesburg, South Africa) for his help with this answer.

Peter,

I imagine this is one of the ones where two or three of my colleagues will post contradictory answers once they see mine, however......

My understaning of locomotory mechanics in birds is that the 'head bob' is partly a result of balance issues. With the heavy flight muscles at the front and just a few feathers for a tail, birds are rather front heavy (their centre of balance lies in front of their feet).

They can correct for this (partly) with their leg muscles. You can lean forward quite a long way without falling over, but you will feel the strain in your legs as you do so. When birds walk though the head 'bobs' not so much up and down as forward and back. The head is quite heavy and so by shifting it back during the walk they can stop themselves overbalancing.

With that in mind, I would not expect many bird-like theropods to bob as they had long bony tails and far smaller chest muscles meaning their balance was much better than a birds.

In the best traditions of palaeontology, there is another possibilitiy though. Some birds have unusual ways of interpreting shapes in the brain. Often you will see birds 'cocking' the head so that only one eye looks at a specific shape when up close. It is possible (though not too likely as many birds do fine without it) that the head bob helps them see better as the eyes will be able to see things at different angles as the head moves - similar to the way we move our heads when trying to make out an indistinct shape at night.

Sorry for the complex answer (that says both yes and no). Overall, i would not expect theropods to bob, or if they did, only a little.

I should add that in our 'links' section there are some websites about fossil hunting. These will give you some good places to search around Bristol and the rest of the UK.

Zoe,

You have asked one of my all-time favourite bits of biology trivia and I am delighted to have got here first to answer it. However, the answer is rather complicted, so bear with me!

First off, your sneeze is what we call a 'reflex' action. It is an action that you cannot control (you can't make yourself sneeze, like you can stick your tongue out). When your nose is stimulated by something that irritates it (like pepper) the nerves send a message to the brain where the sneeze reflex set of nerves send a message to your lungs to make you sneeze and flush out the nose.

When nerve cells are stimulated they pass on a chemical and electrical message to the next nerve cell in the chain. However, if it is a very strong message, this might also leak out and stimulate nearby nerve cells. You can probably now see where this is going.....

So, when you look at the sun or a bright light, your eyes (and their nerves) suddenly have lots of very strong information to pass to the brain. So in addition to passing on their message, they also 'leak' a bit. Part of the path for the optice nerves (from your eyes) happens to be close to your sneeze reflex and so it can be triggered by accident.

So, when you look at the sun, you eyes accidently trigger a sneeze. I hope that's clear for you.

Well Charlie, that is very hard to tell. Kangaroos and other animal that move like that (gerbils and kangaroo rats) have very specialised muscles and so on that rarely show up in fossils. On dinosaur bones we can see marks where the muscles attached to the bones, which gives us an idea of how they worked, but it is still difficult to work out how this might have affected how the dinosaur moved.

Interestingly, there is one set of footprints known that seems to show a theropod (one of the predatory dinosaurs) hopping. However, it is a single hop, and comes after a set of normal walking footprints. So it appears that the hop the dinosaur made was unusual, rather than its normal way of moving. But at least we do know that some dinosaurs could hop, whether any of them normally moved like kangaroos we will probably never know.

Very much so Steve. That is a real shame. The current members of AAB are about 1/3 current or ex Bristol and I know many of them love the place.  A number of us used to do demonstrations there about dinosaurs and palaeontology, and personally I always loved their history of plants section. All of the exhibits were clear and well laid out and the animals well looked after.

As somene who spends his spare time keeping tropical fish I have to say I though their marine aquarium was one of the best around. I am a big fan of zoos and many do incredibly important conservation work, but are often lacking on the education side of things which WildWalk was especially designed to do.

I am very sad to hear that the place cannot continue and I think it is a loss, not just for Bristol and the SW but for the Uk as a whole. If model projects like this that are exceptionally well put-together, I doubt other smaller centres can survive, or would find funding to start in the future. Like this site, the goal of WildWalk was education - get people interested and excited and really good things can happen. Sadly, thats one less organisation and one less place for people to come and learn about the life sciences.

Megalodon is known pretty much only known from teeth. There are a few bits of vertebrae (backbones) that might belong to it, but it is hard to tell. As you probably know sharks do not have bony skeletons like ours, but ones made of cartilage. As a result it does not fossilise well as it does not contain lots of minerals (like calcium and phosphorus) that help fossilisation.

Still, in exceptional circumstances cartilage can fossilise and happily there are lots of fossil sharks known from complete or nearly complete fossil skeletons. Shark teeth of course are still bony which is why so many of them are preserved even when nothing else remains, but many extinct sharks also had bony spines on their backs or in their fins and so these are often found too.

This is a tricky one to answer Ali as it varies so much. Some ampibians spend all their life underwater and so breathe (i.e. get their oxygen and get rid of carbon dioxide) through their skin. Those that do this usually have large gills (like the axolotol) or extra folds of skin (like the hellbender) to increase the surface area of the skin and thus get more oxygen. The male hairy frog even has lots of filaments of skin to help it do this. It makes it look like it has fur, hence the name.
Other desert frogs and toads would soon dry up if they kept their skin moist like most other amphibians and so breathe only through thir lungs (like we do) when they are not in water.
As for say, a 'normal' frog on land (like the European frog)  this varies considerably. Frogs use the lungs primarily to take in oxygen and the skin to get rid of carbon dioxide, but the amout that each is used varies with humidity and temperature. Breathing through the lungs seems to account for about 80% of the oxygen uptake and 30% of carbon dioxide loss under 'normal' circumstances, with the skin therefore accounting for the reverse (20% oxygen and 70% carbon dioxide).

I should add to Graeme's answer that we do know of a few dinosaurs and other ancient reptiles from Antarctica. Not surprisingly the conditions there make fossil excavation very, very hard, but a number of dinosaurs bits have been discovered. This includes the wonderfully named Cryolophosaurs (the frozen crested lizard), a large carnivore with a flange of bone on its snout.

Well Jerry, you really have hit the nail on the head. Since this site covers all ages from 5 and up, having dinosaurs within birds, or birds within reptiles would consfuse people who didn't know (and lets face it, reptiles are paraphyletic  anyway).

Still, none to my surprise we have had a number of questions on the bird-dinosaur link so there is plenty of information on the site about it.

Finally, this site is less than a week old. We are still setting up the contact e-mail, the 'labcoat' files and sorting out the forum categories for questions so nothing is finalised yet. Basically as you said we need some artifical groups to make things as easy as possible for as many people as possible. Those unfamiliar with the bird-dinosaur link will not be caught out and those who do know will soon find the section they are looking for.

Thanks for the feedback though, please check back with us later.

That’s quite a question, but you have picked up a few misconceptions there. I’ll try to pack it all into a reasonable reply post, but do send us another comment if you want more (and leave us your contact details).

Reproductive success is by no means the be-all and end-all of success in terms of passing on your genes. Animals must survive long enough to reproduce, and few survival traits are linked to sexual selection or to sexual characteristics. Quite the reverse in fact if you look at how sexual selection operates. Look at this recent paper (abstract here) on the changes in limbs in lizards. Limb length changed twice in less than a year in response to the introduction of a new predator. A change in limbs and behaviours allows only some lizards to survive to reproduce, so their mating success is directly tied to this, if not their ability to compete successfully for mates.

You have also used a very strict definition of 'evolution', assuming that it must be an active trend. Traits may appear that have no obvious function (like red hair in humans, or a 6th finger), but if they do not affect the survival of an animal, or its reproductive success then (all other factors being equal) there will be nothing to stop it from passing on its genes and this trait may spread through a population by genetic drift. Reproductive success does not ‘have to happen’ to change the genoype of a population. However, these traits have still evolved, as they did not exist in earlier generations. They may subsequently become 'functional' (red hair might be deemed more attractive, or a 6th finger might help climbing) but this does mean that evolution has not occured.

Novel adaptations can certainly drive evolution however, see some examples here. Obviously the success of groups like birds and bats is in response to their ability to fly and the evolution of flight has allowed them to exploit new niches and speciate and diversify as a result. With much of this work being done by the Gants on Darwin’s finches. At times of great change (after mass extinctions say, or the initial colonization of land) then niches are available to be exploited, and otherwise unsuccessful or uncompetitive adaptations may (temporarily) become established (evolution may go a little nuts) but in times of stability, the better adapted organisms will come to dominate (e.g. the rise of the dinosaurs in the Jurassic). Niches are plastic things and as environments change (over space and time) and organisms, evolve, adapt and compete, they will shape their own niches and those of other species around them.

As for convergent evolution. There are a limited number of ways of solving certain problems (e.g. feeding on termites) with certain body plans and so it is somewhat of an inevitability. In some cases (e.g. birds, bats and pterosaurs) a remarkable problem (flight) can be solved in very different ways, but in other, conservatism of shape is clearly the best solution (whales, penguins, icthyosaurs, tuna) and so evolution will eventually stumble on the ‘best’ solution and shapes will converge.

You also asked about books, take a look around. A quick search on Amazon for “evolution” and “adaptation” found a few dozen popular and more technical science books. A good start would be the Dawkins books The Blind Watchmaker and Climbing Mount Improbable.

Well Will, there certainly was such a thing as Giganotosaurs (yes, your spelling is right!) and it was indeed 'bigger' than Tyrannosaurs. Several fossils of Giganotosaurs have been found from the rocks of Late Cretaceous in Argentina, and it is one of the biggest known carnivorous dinosaurs. It was relative of Allosaurs (although it lived much later) and may have reached more than 15 meters in length! This is quite a bit more than T.rex, although T.rex was much bulkier and as a result was probably a heavier animal. Above is a reconstruction of the skull of Giganotosaurswith that of a human!

Giganotosaurs lived at the same time and place as the largest known dinosaur, the enormous Argentinosaurs that may have been up to 50 metres long, and weighted 100 tons!!! As a result, it has been suggested that Giganotosaurs was actually a pack hunter and took on these huge dinosaurs in groups. Here is a picture of a reconstruction of the two dinosaurs.

As for dinosaur intelligence it is a difficualt question to answer. Certainly some dinosaurs would have been quite smart compared to living animals. We can get an idea oof both an dinosaurs brain size, and how it was made up by the bones that surround it. From this we can see how big the brain was and what parts were devoted to eyesight, smell etc. There is also a general correlation of intelligence with the size of the brain and the size of the animal. Large animals need large brains, so a small animal with a large brain was probably quite smart. Certainly some dinosaurs (notably the advanced predators like Troodon and Deinonychus were about as smart as some modern birds like ostriches. Our own Darren Naish discussed some of these issues recently, look here for more. http://darrennaish.blogspot.com/2006/11 … sited.html

As for why more dinosaurs didn't get more intelligent sooner, well thats impossible to say. Probably they had no need to, they only had to outsmart each other, so if everyone was at the same level there would be no big evolutionary pressure to get smarter. Darren's post looks at some of the consequences of super-smart dinosaurs and how they might have evolved.