(posted in Evolution)

No more so than macro-evolution.  Micro evolution might make small changes to organs.  Over time, this will manifest as macroevolution (as the names suggest, they are the same thing but at different time scales).

(posted in Fossils)

It's very, very hard to say from the pictures, but I would be inclined to say that the fracture pattern indicates it's a nodule of some kind.  An egg would be unlikely to break in that way, and if it did there's no reason it owuld be preserved intact but broken (If the peices broke during burial, it would be more flattened, and if the broke before burial it wouldn't be whole).

However, that's just based on the photo.  You might have more luck taking it in person to a local museum.

(posted in Evolution)

This is a common image that is wrong in a number of regards.

Firstly, we did not come from chimps, but share a common ancestor with them. As such, the there is not 'millions' of the ancestor around today.

Secondly, we have numerous examples of intermediate species, and the standard creationist argument is always to ask for another intermediate between the intermediates.  Usually this is found, and then further intermediates are requested, and so on, and so on. There is an episode of the wonderful Futurama that parodies this excellently.

To direcly answer your question, the intermediate species have become extinct, either dying out or giving rise to different species (It's entirely possible that Homo sapiens, modern humans, were responsible for the loss of at least some extinct hominid species like Neaderthals (for instance see: https://en.wikipedia.org/wiki/Neanderthal_extinction))

With regards your philosophical discussion, check out Russell's Teapot [http://en.wikipedia.org/wiki/Russell%27s_teapot], which is a philosophical argument for why it doesn't make sense for everyone to say "well maybe there is a god" (which in itself would require 'god' to be defined first). However, each to their own etc...

I'm not sure what your issue is with convergent evolution. We see it multiple times in the living world.

(posted in General Biology)

Looks like a bird sternum (or Keel). I couldn't tell you which bird though... perhaps another expert here can?

(posted in Human Biology and Evolution)

It depends what the task is as to which fingers are used more commonly.  Precise work might use the thumb and fore-finger because they oppose, but grasping may use all fingers in order to increase the grip.

Hi Angela, I think in order to help we'll need a better photo with a sense of scale, and to know where in the world you live.

Even in the most casual tone, genus should be capitalized, species not, and both should be italicised.

General terms like 'allosaur' do not get capitalized* or italicized.

*except at the start of sentences, obviously.

(posted in Fossils)

My Trilobite expert colleague agrees with you that it's a calymene of some description. They suggested it might be a Flexicalymene.

(posted in Genes, Genetics and DNA)

I may not be seeing the research you're referring to, but it looks like in mice the only hair color changes I've seen have been returning from albino to a colour, rather than changing from one colour to another. (It may be possible to define hair colour before birth, but I haven't seen it during the animal's life).

So...  could be some time before we see it on the pharmacy shelves!

(posted in Fossils)

Really hard to tell from the photos I'm afraid Martin.  But if this is found in an area with lots of flint, my first guess would be that it's a [heavily weathered] rugose coral of some sort. However, I can't see any distinctive features that would verify that.

(posted in Human Biology and Evolution)

It can be highly variable, depending on how the remains are buried/preserved.  Generally the densest bones will be most durable, including as you say the Coccyx and perhaps the skull.  Often the bones may not remain in one peice but shatter, and so you may find fragments of many bones, but not the whole thing.

Sadly this is one of those cases where the taught definition isn't as strict, or well defined as implied. The species concept you refer to is only one of many, and it has some issues firstly among plants (many of which can hybridise readily), and secondly with close, or recently diverged groups. A 'species' is just a human construct - a label only. While Neanderthals and Denisovians were seperate groups (and, are in fact seperate morphospecies) they were apparently close enough to modern humans genetically to interbreed.

Take a look at our own guide here; http://www.askabiologist.org.uk/from_th … s-concepts

And also the wikipedia page highlights some of the complexities:

http://en.wikipedia.org/wiki/Species#Bi … definition

(posted in Fossils)

Sorry Annie, there's nothing strikes me in the images as being a fossil, though perhaps other contributors here can see something.

(posted in General Biology)

live science tends to be fairly reputable, and they have a short article here:
http://www.livescience.com/33179-does-h … years.html

Simply put, most cells do get replaced, but some, importantly the neurons in the brain, do not.  I think your suggestion of enamal is correct, but white blood cells do die and get replaced (apparently every year or so).

Fossils are almost always found at or near the surface. It's very rare for palaeontolgists to go out and just start digging.

So yes, in some cases that means the surface is very ancient - but it doesn't mean it's always been exposed. Rather, it was laid down, buried, and then re-exposed millions of years later.

Often, it's only part of a surface, because the rocks tilt, so if you go to far one way, the surface you are stood on will get 'younger', and the other way 'older'

Evolution is as solid as the theory of gravity, nuances in the mechanisms are hotly debated, but at a fundamental level, it's difficult to concieve of a way it could be shown to be completely false.  Even the 'devonian rabbit' (the idea that an animal could be found hundreds of millions of years before it's supposed ancestors appeared) wouldn't necessarily destroy the entirity of evolution, rather it would shake up the mammal and maybe tetrapod phylogenies (though it would certainly cause a fuss!).

A lot of people think it's reasonably that life could arise from inanimate objects dur to chemical reactions - viruses and very simple bacteria really aren't more than tiny bags of chemicals (and the former is debated as to whether it is even alive or not). However, until someone can demonstrate the process*, it remains a bit of an 'I reckon'.

*Given that we have trouble classifying viruses as life or not, my opinion is that in attempting to demonstrate abiogenesis, we could hit the hurdle of not being able to say whether what is produced is life or not.

This is completely cultural.  Look at the ideals of beauty jsut 50 years ago or so and they are very different in body shape and facial features.

Perhaps more to the point, is that all the beautiful men and women you see in the media don't exist today - practically every single image is digitally manipulated - heavily.  I don't particularly want to link to sites with lots of images of models in bikinis, but if you google for photoshopped magazine images, you will find an unbelievable amount of examples.

Some ornithopods were obligate quadrupeds- they could only walk on all four legs. It's perfectly reasonable to assume that they could have been pretty adept at running, though it's unlikely ever to have become like a gazelle or horse simply because the muscles and bones aren't arranged the same.

If you mean simply 'as fast' as gazelles and horses, well, I don't think there's been enough research to say for sure, but they could probably run pretty quickly to escape predators.

I've not heard of, nor can I find any information that that is the case.

The rib cage needs to expand when you breath, hence why it is made of seperate bones that can move together and apart.

Generally it would be a masters and then a PhD (some peope don't do a masters and go straight to PhD, but you generally need a very good first degree to do that these days).

After a PhD, you would then do 1-3 Post-Doc position lasting 1-3 years each, and then fingers crossed a lectureship would come up.

To work in a museum, you might instead look at a Masters in museum studies, and then enter into curatorial work.

Check out our How to Become a Biologist page: http://www.askabiologist.org.uk/from_th … -biologist

Simply, evolutionary history.  The 2-3-3-3-3 pharangeal formula goes back pretty far evolutionarily (I think right back to basal mammalia). It's easier to lose a joint than to add one, so lineages tend to see joint reduction, but then rarely (if ever?) joint increase.

If we go back even further to basal reptiles, the forumal is 2-3-4-4-5.

[side note - apparently the forumla of cetaceans (marine mammals) is 2-12-8-1. No doubt the lack of weight bearing and and the strong selective pressure for increased surface area allowed an increase in phalanges]

Why did it arise in the first place?  Not sure.  If I were guessing I'd say those inside digits (thumb and big toe) were the most weight bearing (which is still the case), and less joints = more stability in the weight bearing digits.  But that is just speculation.

(posted in Evolution)

Your science teacher is right, but the scenario as a whole is really complex.

Between a few hundred thousand years ago and a million or two, there were multiple species of hominid, all more or less as intelligent as each other. Neanderthals, for example, were around at the same time as us.  However, it is now believed that the two species interbred and the Neanderthal populations were assimilated into Homo sapiens.

One reason panthers, lions, tigers etc all co-exist is that they exist in different parts of the world, and occupy different niches (panthers in the jungles of south america, tigers in tthe jungle of india/china, and lions the savanah of africa).  So because they occupy different places and environments, they are isolated enough to breed seperately and form slightly different species. It's worth noting that these examples are all from the same genus. When humans spread over the world, they were less isolated that the Panthera examples.

What a fun question.  However, it's difficult to answer without knowing what 'tiny' means.  I mean, a horse 3ft tall is tiny - relative to a horse.

Given the biomass issues involved, lets assume that you're referring to all the spiders turning into horses of equal body mass (so very very tiny!):

Well, the simple answer is that this would be identical to if all spiders suddenly went extinct - spider sized horses would be unable to feed, or even to move around easily (as they can't climb up walls). Best case scenario is that those tiny horses that can get to a grassy area quickly, and start munching (though I'm not sure the energetics of converting cellulose heavy grass would work with a mammal stomach at this size).  There would be an explosion of insects (on average, a house spider eats 2000 insects a year), and subsequently other insect predators would boom, filling the niche left behind by the spiders/sad tiny dead horses.

If the horses were able to process grass, we may also see some kind of wierd effect on fields, with bare patches appearing as if the grass is diseased, as tiny horses begin to devour what they can.

Spider mites.  I think (still quite small in that image).

Hi Yisroel. It's hard to directly answer your questions, as 'smaller-scale' evolutionry changes could be anything. The worry is that we get into the creationist argument that there should always be another intermediate...

It comes down to what you consider 'smale-scale' changes to be. Darwin talks about the theory - all ancestors are gradually evolving, with the reality - not all ancestors are preserved. However complete the fossil record, be it 1% or 99%, your quotation from Darwin is still correct - we can never see all ancestors, so the very finest, contiuous change, is unlikely to ever be found.

(We could argue that archaeopteryx is a gap-filler, or we could use the myriad of feathered dinosaurs which provide dozens of transitional forms for the same transition (dinosaurs->birds)).

So if I read your question correctly, your reading is that Darwin found it unreasonable to suggest palaeontologists would find all small-scale transitionary forms, which is fair, and I don't think direct examples of predicted gaps and them being subsequently filled affects that.

I can't answer 1) and 2) I'm afraid, as it's a while since I've read Darwin and I can't recall distinct predictions about gaps being filled. Perhaps another site expert can be bit more specific in this regard.

(posted in Fossils)

There are certainly environments where the liklihood for fossilization is extremely low - Basically anywhere that is eroding rather than depositing.  You would be unlikely to get fossilization at the top of a mountain for instance (because the top is always weathering away).

However, the animals that die in such places will likely have their remains end up in the same place as the eroded sediment.  So a goat that dies on a mountain, for instance, would likely get washed down the side of that mountain and end up in a river channel further down where sediment is being deposited.

This is known as allometry - the change in shape as size changes.  Many animals are subject to this (juveniles are not just miniture adults).

It's not always clear why this is, though it results from different parts growing at different rates (the brain vs the digestive system, for instance).

I can't find much info on the specifics of why for humans, but here's a cool article on Allometry: http://www.nature.com/scitable/knowledg … g-13228439

You can be a palaeontologist without maths, see here:

http://www.askabiologist.org.uk/answers … hp?id=7803

and also here:

http://www.askabiologist.org.uk/answers … hp?id=8144

It is very useful though, both in terms of getting accepted onto a degree, and for use in the science itself, so if you can get to terms with maths, it would be a help.

To your first point, unless there's a glaring reason not to, the best bet is probably to pick whatever interests you most, based on course descriptions and your previous year's experience.  Don't worry about specializing or diversifying at this stage - it'll all count towards a Zoology degree.

To you second point: The best bet will be to speak to the lecturers of the coures/areas you enjoy most, and ask if they have need of any lab volunteers, or research assistance.  You may be able to get vital experience in your own University, and doing that you'll be able to try several things, and also build up good relationships with potential referees.

Your current volunteer work is definately a goot step in the right direction.

Great question.  I don't know of any research looking into this.  A quick search seems to suggest they didn't have nostrils, and may in fact have had blow holes, though I can't substantiate this.

I'll keep looking into it and get back if I find anything else.

Afraid not.  There's no evidence at all that we are descended from wolves.

There is a wonderful fossil record of transitional forms towards humans (see here: http://www.palaeontologyonline.com/arti … al-apes/), and genetic evidence indicates humans and apes are most closely related.

Many of the factors you mention are either anecdotal or equally applicable to apes.

I'm not sure it's so clear cut.  Perhaps this is why learning to ride a bike is not trivial, or why people get car/bus/motion sickness.

Perhaps we just habituate to these situations.

I'd be interested in what others have to say.

(posted in Fishes (Including Sharks))

Not really, it's still half for up and half for down, it's just different halves (dorsal/ventral) than the split used in side to side (left/right)

This is one of those physiological questions that may never be directly answered from the fossils.  However, given the way that birds and crocodillians defacate (unless I'm wrong that crocs are similar), it's reasonable to think Dinosaurs did it the same way.

I'm not as up on my flowers as I could be, so I can't say for certain whether this particular image is real or 'shopped.

However, I can say it's a Camillia, and given the forms of other plants
(e.g. http://commons.wikimedia.org/wiki/File: … nica.jpg), it seems plausible that this is a real flower that has maybe been aggressively selected for by breeders.

A further googling has given me confidence that this is a real image (or at least if this particular image is a fake, it's a fake of a real thing).

A second AAB-questioner recently got in touch with me about this post, as he had also found one (new picture with 1p for scale below). If anyone has any ideas, I'm sure he'd appreciate them.

Hi Patrick,

  That sort of detailed palaeobiological question is really hard to test from fossils.  That said, I think you've made a pretty logical, sound, inference from modern reptiles.  It seems to me that you'd be justified in depicting dimetrodon this way.

Well, as always, there isn't a simple answer.  It depends at what point you consider yourself to be a paleaontologist, or what path you wish to take.  If we say a researcher, then in the UK system, you'd be looking at:

An undergraduate degree: 3-4 years
Possible a Masters degree: 1-2 years
A PhD:  3-5 years

So there's a total of 7-11 years.

After that, people typically have 1-3 post docs, which are 1-3 years each (so, 3-9 years of post-doctoral work) where you are employed, but not necessarily in a permernant position. Some people have less time in post-doctoral positions, some more.

(posted in Evolution)

I think there's a misreading/simplification of newton's laws here...  a car would similarly fall into the category of self moving, as would of course pretty much all other animals.

At a basic level, you could consider that your torso is being pulled/pushed by your legs. Your legs are incorporating gravity to pull you. Muscles pull against bone, and the skeleton transmits that force to the ground (or other substrate).

If you were in a gravity-less vacuum (i.e. in space and unsupported) you would be unable to move (beyond fruitlessly waggling your arms and legs).

(posted in Evolution)

All animals have a common ancestor, though for such distantly related groups as gastropods and tetrapods, it will be very far back indeed, and there will be a lot of groups in between (fish for example).

Unless I'm mistaken, you'd have to go right back to the bilateria to get a common ancestor of Gastropods an tetrapods:


Maybe a little up the tree from there...

(posted in Evolution)

The worms need to rise when it rains/the tide comes in, in order to feed, so it would be very difficult for them to evolve away from this response.

Well, it's not really a question where sending pictures is going to help.  The answer is much the same as for the reason that there are both large and small mammals alive today; some animals evolve to exploit different food sources, and in some cases being large is an advantage (e.g. for digesting certain foods, or avoiding predators).

(posted in Fossils)

Feel free to post a link to a photo here on this site.

(posted in Evolution)

It's unlikely that something like T. rex would have bobbed it's head, because that head is so massive, it wouldn't make sense to have to move it back and forth. 

It is feasible that the smaller, more avian theropods could have bobbed their heads when walking though.

The truth is, it's still not certain why some birds do bob their heads when walking.  Most research tends to suggest it's a visual stability thing, but in that case it's very difficult to extrapolate back to whether dinosaurs did this.  The fact that not all birds do it (in fact, a relatively small proportion) means it would be extrapolating a bit too far to say that non-avian theropods did it too.

Not really, it's incredibly difficult to assess things like that from the fossil record.

However, you may find this article of interest, which compares brain endocasts of Allosaurus to other animals:

http://onlinelibrary.wiley.com/doi/10.1 … CO;2-W/pdf

(posted in Mammals)

Sheep or goat sound about right, but from the photo we've only really got the teeth to work with.

A fish-specialist colleague thinks that this may be a member of the Cod family (compare your pictures with these of a Haddock: http://www.biolib.cz/en/image/dir0/id10 … mflt=225).

However, she warns that without locality information, this is just a best guess!

It's also rather the wrong way of thinking about it.  Instead of 'what do I need for a lab', the question should be 'what do I need a lab for?'