(posted in Evolution)

Yes, all those are good indicators; but remember that they way they appear in the output of a a cladistic analysis is just as a branch with many character transitions. Cladistics itself knows nothing of time passed, or of which characters are exaptations. All it knows is nodes separated by arcs with character transitions on them.

My first thought is that it looks like a humerus (upper arm bone). My second is that the foramen -- the hole that penetrates it towards the narrower end -- is the kind of thing you find in bird skeletons. But it doesn't look like the humerus of any bird I can find. Hmm. Maybe someone else has a better idea?

(posted in Fossils)

It definitely looks like bone: the texture is pretty characteristic. As to what bone -- it's very hard to say. I don't know what the tab projecting upwards from the middle would be. Anyone?

Can't you just keep them in pots on a small table in front of the poster?

There are no rigorous definitions of what's microevolution and what's macro. They're just broad terms that are as useful as the uses you find for them. If you're studying the differences between Homo habilis and Homo sapiens then the evolution of humans from apes will appear macro to you; but if you're studying the differences between prokaryotes and eukaryotes, it will appear micro.

No. Cladistics only produces the best (most parsimonious) tree that has as its leaves the taxa that you specified. You might have a matrix where your taxa are a hundred recent birds, no Mesozoic dinosaurs and a crocodile. All that will happen is that you'll get back a tree where the first divergence point is between the croc and everything else. When you looked closely at that tree, you'd see many state transitions betwen the root and the croc, and between the root and birds; and that would be your clue that there were a lot of organisms missing.

I am truly sorry to disappoint you, but nothing like what you describe could exist. At 123 m long, its proportions would not be completely different from those of a 123 tall human. A healthy human male of 1.8 m might mass about 80 kg. Your animal is 68.33 times as long in linear dimension, which mean 68.33^3 = 319079 times as voluminous. That gives a mass on the order of 25,526 tonnes, whereas the biggest animals known to have walked on land where not much more than 100 tonnes. You simply can't credibly propose an animals 255 times more massive than the biggest we know.

Wikipedia is superb for this kind of thing. Honestly, it's the first place I would go.

To be honest, I struggled to understand the proposed statement.

My advice would be to leave the ID section out, at least initially. Better to start small, and see whether there is a demand for such a thing.

(posted in Evolution)

Actually, a cladistic analysis will not inform you if you do include the actual ancestor -- or any of the ancestors of subclades. It will always arrange the taxa at the leaves of a tree, so that the root is a node connecting two arcs, rather than an actual taxon.

I'll go further: a clade is always defined as comprising the set of all descendents from a single common ancestor. That's what makes it a clade rather than a grade or some other kind of taxon. Evolving out of your clade (or rather, your clades, since you belong to many) is by definition impossible. You will always be a primate, a mammal, an amniote, a sacropterygian and a vertebrate.

It's not too early to say that dinosaurs had feathers; they did have feathers.

It's too early to say whether those feathers evolved from bristles.

It's too early to tell. The various integumentary structures that we know about for dinosaurs (true feathers, protofeathers, filaments, quills, bristles) are scattered all over the family tree in a random-looking way; some of these are only known from single specimens. Hopefully the picture will become clearer as we get more and better specimens that preserves these structures.

If I had to take a guess: these structures probably share a single evolutionary origin, but diversified in various ways in different lineages. Feathers as we know them today probably did not evolve from anything like the Psitaccosaurus bristles, but from something that would have looked more like shaggy fur. Probably. Maybe. Check back in a decade, and we'll see how things are looking :-)

Most snaked lay eggs, but some are viviparous (give live birth) -- including the boa constrictor. Others have an intermediate condition called ovoviviparity, in which baby snakes mature in eggs that are held inside the body until ready to hatch.

Basically, "snakes" is a broad term that encompasses 3,400 species and a range of wildly different lifestyles. Almost no generalisation about all snakes will be true!

Some did, at least -- Psittacosaurus, for example. For most, we can't tell because the fossils aren't good enough. Although bristles are pretty hard, they're not as hard as the bones and teeth that typically fossilies, so it's very possible that we have skeletons of many dinosaurs what were bristled in life, but whose bristles didn't survive.

See https://en.wikipedia.org/wiki/Psittacosaurus#Integument

(posted in Mammals)

Giraffe are artiodactyls, or "even-toes ungulates". That means they have an even number of toes, like cows, pigs and sheep; and unlike horses and rhinos. Specifically they have cloven hooves, so two toes per foot for a grand total of eight.

Of course, back in the good old days, scientists would just have determined this experimentally. But you know how it is, with bleeding-heart liberal Ethics Committees :-)

Malena, the main thing to bear in mind is that everyone loves dolphins and whales, which means that marine biology (especially dolphin biology) in an incredibly competitive field to get a job in. That means you really need to give your studies your absolute best efforts if you're going to have a realistic chance. Good luck!

What an interesting question.

In general, the bigger an animal you drop off a skyscraper, the worse it will fare. An ant will just walk away; a mouse will quite possibly by OK; a human will die; an elephant will splash. That's because the kinetic energy that has to dissipate on impact is proportional to mass (with scales with the cube of linear dimension) but it's doing this over an area proportional to the square of linear dimension. Also, the energy is proportional to the square of the velocity, and terminal velocity is higher for larger bodies.

But the obvious exception applies in the case of animals that can slow their descent. Drop a pigeon off a skyscraper and it will just fly away. Drop a "flying squirre" and it will glide to the ground. Where does a chicken fall on this scale? I don't know, but my guess is that the great majority of breeds can glide at least well enough to avoid injury on landing. A few of the bigger breeds ... maybe not.

Sure, it's possible. But how could we ever know? What experiment could we perform to test the idea? What evidence could we find that would confirm (or contradict) it? Unless we can come up with something along these lines, then the idea of pair-hunting in Velociraptor is pure speculation, not science.

The biggest pliosaur that we have good osteological evidence for is probably Kronosaurus boyacensis from the Aptian of Colombia. This has a 2360 mm long skull, and a total snout-to-vent length of 7250 mm. In the absence of a tail, we can't know what the total length was in life.

There is an excellent overview of pliosaur body size in this open-access paper: http://journals.plos.org/plosone/articl … c4.sec2.p1

Yes, it's possible; but it's also possible that Utahraptor hunted in packs, while Velociraptor was a lone hunter. There is simply no way to tell from the fossils. As the example of lions and tigers shows us, there is no way to infer behaviour from skeletal morphology.

There is no compelling evidence that they either did or did not. Most likely, some species did and some did not -- just as lions hunt in packs, but tigers are solitary.

You've not given us much to go on!

If you have a specimen of this organism that you think may be a new discovery, you should take it to your local museum -- somewhere there will be able to advise you, and judge whether it's sufficiently likely to warrant further investigation.

If the organism is still in its natural habitat, then take photos, and show them to the local museum.

Ah, c'mon, David, you can't write off a whole family of 60,000 species just because of a few rotten apples :-)

Well, there is a long, long way to go before you can achieve this dream.

But the best place to start is probably with whatever your school biology textbook has to teach you about genetics. From there, you can go on to the Simple English Wikipedia page on Genetics (https://simple.wikipedia.org/wiki/Genetics) and its many linked pages; and once you feel you've mastered that, on to the main Wikipedia page (https://simple.wikipedia.org/wiki/Genetics).

The Wikipedia introduction to genetics may also be helpful: https://en.wikipedia.org/wiki/Introduction_to_genetics

The two biggest factors that make modern birds move very differently from Mesozoic theropods are their lack of a heavy tail, and their sheer small size. Something like T. rex would have walked very differently from a chicken.

I would be very wary of over-interpreting the size estimates in popular books: they tend to be recycled tenth-hand from estimates based on very incomplete specimens, and often bumped up somewhat because "there were probably bigger individual".

I thought it was pretty much the definition of a stem-cell that you can't tell what it's going to turn into?

At present, we can't do this. We can model the brains of very simple organisms, such as the nematode worm C. elegans, because it has only 302 neurons, which have been completely mapped: see https://en.wikipedia.org/wiki/Caenorhab … search_use

But human brains have about 100 billion neurons. Not only is that 330 million times as many as in C. elegans, but the number of potential connections between the neurons scales with the square of the number of neurons, so there are 110 quadrillion times as many possible connections.

Not only that, but human brains vary enormously from person to person.

Do you mean a strand of DNA so short that it has only one base-pair in total, or a strand made up only of AT pairs or only of GC pairs? In both cases the answer is "it's very unlikely, but nothing in particular would happen to it."

BTW., the human genome contains about 3 billion base-pairs. That means it's more likely than not that any given person's genome contains at least one sequence of 16 consecutive identical base-pairs drawn.

Dinosaurs are real, as you can easily verify for yourself by visiting a dig site and seeing the bones come out of the ground. Like all organic matter, bones will decompose given time exposed to decomposing agents such as microbes. Fossilisation occurs when these agents can't reach the bones -- for example, because they have been buried in a mudslide and in volcanic ash.

(By the way, the spelling is "dinosaurs"; and beginning a question with "Ok, so" is merely distracting. Best cut straight to the point.)

Precisely -- breeds (usually used for animals) and varieties (usually used for plants) are more specific classifications within a species. So for example the herbaceous daisy Ursinia chrysanthemoides var. geyeri is not just genus Usina, species chrysanthemoides, but more particularly, of all the varieties of Ursinia chrysanthemoides, it's the variety geyeri.

Also, you might try writing to Andy Farke, who was making a contribution to dinosaur palaeontology in his teens, and may know more about specifics. He's on , and a very helpful person. You can tell him I sent you.

Great that you got a helpful response from Kristi, who has done some great descriptive work on sauropods, especially the Malagasy titanosaur Rapetosaurus.

In general I would encourage you to simply approach palaeontologists working in local (to you) universities. Write short, respectful messages indicating your interest in helping with fieldwork, and emphasising that you really do want to help -- that is, work hard at difficult, tedious and uncomfortable tasks, rather than just coast along for the ride and the experience. My hunch is that if you send a few of these, you'll strike gold at least once.

The obvious questions about all these huge skeletons from the 18th Century are:

1. Where are they? If they were accessioned at credible museums, they will still be in collections, or at least there will be a record of how they were disposed of. But we see no such records.

2. Why aren't we finding any such remains now? We certainly wouldn't have been able to exhaust a plentiful fossil record in the 1800s, just as we didn't exhaust the fossil dinosaur records.

I'm afraid the only realistic conclusion to draw from the absence of evidence of these giant humans is that the bones never existed.

Two different animals. Compsognathus was a coelurosaur theropod; Procompsognathus, while not a direct ancestor, was a forerunner and belonged to the more primitive coelophysoid group of theropods. It lives about 60 millions years earlier.

(posted in General Biology)

Yes -- we have an oddly positioned epiglottis which enables us to form more sounds, and so use language. An unfortunate side-effect is a tendency to choke. I understand that babies have their epiglottis in a position that makes them less likely to choke, and it migrates as they devleop. (David -- is that right.)

I am sure you're right -- this will be the result fo selective breeding, like pretty much all domestic animals: pigs with lots of flesh, cows that yield lots of milk, etc.

Maybe the real question is: why did anyone take it into their heads to breed smaller chickens? You would surely expect the opposite. Wikipedia suggests "Bantams are suitable for smaller backyards as they do not need as much space as other breeds".

If you mean you want to work on fossil digs, then I would not be too put off y the lack of fossil clubs. Find universities in your area that have Earth Sciences departments, look through the faculty pages, and find staff members who are working in palaeo. Drop them a line, asking whether you can help with any of their field work. If you're able to fund yourself, and a hard, consciencious worker, you could well find something this way.

But what does it mean to "do palaeontology"? Usually, it means reading, thinking, and writing. Forming hypotheses, drawing conclusions, supporting them. You can do that at any age (and several now-well-established dinosaur palaeontologist including Andy Farke and Steve Brusatte were involved as teens). See http://svpow.com/2010/11/12/tutorial-10 … ntologist/ and related tutorials.

(posted in Evolution)

It's a matter of probability. You might happen to find a fossil that's a dead-end mutant (although note that most dead-end mutants die very early, usually before birth). But the chance that many or most human fossils fall into this category is vanishingly small. If you throw a dice and get a six, that's probably blind luck; but if you throw 100 dice and they all come up six, you have to assume that some other force is at work (e.g. the opposite sides are magnetised to the surface you're rolling on).

The other thing is that you can in general see progression through time, with fossils changing along a trajectory. Now there are plenty of exceptions to these trends, for at least two reasons. One is that evolution is a branching tree rather than a linear progression, and we usually see sampling from all across the tree; the other is that the environmental changes that drive evolutionary change are not constant. Nevertheless, trends are often visible through time.

The same for fossils as for living organisms: there is no objective way to determine whether two individuals are sufficiently similar to belong to the same species, or to the same genus. It always comes down to the judgement of a taxonomist.

Ah, gotcha. The species you're referring to is Deinonychus antirrhopus, but Greg Paul in his 1988 book Predatory Dinosaurs of the World wrongly thought that Deinonychus was the same species of Velociraptor, and so used the combination Velociraptor antirrhopus. As far as I'm aware, literally no-one has followed that usage.

"They were too large, and too clever (though the real ones were still remarkably intelligent" ... Actually, we know almost nothing about the intelligence of any Mesozoic animal. Maybe real Velociraptors were as clever as the ones in JP.

Your palaeontologist friend is mistaken: Velociraptor mongoliensis is a perfectly good species, and has some extremely good fossils.

The second species, V. osmolskae, was named by Pascal Godefroit and colleagues in 2008. Here is the abstract:

--
ABSTRACT—A new dromaeosaurid dinosaur—Velociraptor osmolskae n. sp.—is described on the basis of associated paired maxillae and a left lacrimal discovered in Campanian (Upper Cretaceous) deposits at Bayan Mandahu (Inner Mongolia, P. R. China). The maxilla of this new taxon is characterized by its long rostral plate and its enlarged, teardrop-shaped promaxillary fenestra, which is as large as the maxillary fenestra. The teeth are robust and the serrations are weakly developed on their distal carinae. This new taxon appears more closely related to Velociraptor mongoliensis, from the Campanian Djadokhta Formation in Mongolia, than to other dromaeosaurids described to date. The identification of the Bayan Mandahu Velociraptor as a distinct species is in keeping with the taxonomic distinction of the entire dinosaur fauna of this locality. Minor regional differences among Djadokhta-like localities in regards to their dinosaur faunas may reflect either some kind of geographic isolation, or small differences in their age or in their paleoenvironment.
--

So it's based only on fragments of a single skull, which are not enough to reliably distiguish it. It might indeed be a new species of Velorirapor as the authors propose, but restudy and especially new material if any is found could result in its being reclassified as just damaged or naturally varying V. mongoliesis material, or as a new dinosaur (not Velociraptor at all).

I've never heard of a third species.

I think your point #1 is wrong: feathered wings are just as good at generating lift as mebranous ones -- the reason birds have huge pectoral muscles is for flapping, not gliding.

I doubt #2 as well.

But #3 seems correct: membranes tear, and it's virtually impossible for them to be used in that state, whereas loss of a feather or two is not that big a deal for a bird.

Finally, I think the dominance of birds over bats in most ecosystems suggests that the avian system is better -- certainly it enables them to reach much larger sizes. But the very different membranes of pterosaurs enabled them to get even bigger.

Sorry if I'm being dense, David, but I'm not really sure exactly what you're asking.

Actually, the possession of lips and cheeks is still somewhat controversial for dinosaurs. The main evidence for lips is the formamina -- small holes -- around the outer edge of fossil jaws. In life these channels would have caried the nerves and blood vessels of the lips.

I think questions about animal "pain" can be a bit leading. I don't think that what animals experience is really the same thing that humans due: pain is a complex thing that involves self-awareness. I don't mean to minimise the seriousness of animal discomfort, and certainly not to excuse cruelty towards animals, but I do want to warn against over-anthropomorphising.

As far as I know, bird eggs are the same size irrespective of the sex of the bird inside.

I don't know about bird/reptile/monotreme fertility cycles. Hopefully someone else will answer that part.

Since we don't know let me chuck in a couple of guesses.

Could they be cuttlebones, the internal shells of cuttlefish?
https://en.wikipedia.org/wiki/Cuttlebone

Or could they be tests of some kind of sea-urchin?
https://en.wikipedia.org/wiki/Sea_urchin#Endoskeleton

I doubt they are actual bones.

Beautiful photography, though!