Two-headed Reptile Fossil Found in China

[TheBORG] writes "A tiny skeleton from the Early Cretaceous shows an embryonic or newborn reptile with two heads and two necks, called axial bifurcation ('two-headedness') (a well-known developmental flaw among reptile species today such as turtles and snakes) was found in China by French and Chinese paleontologists recovered from the Yixian Formation, which is nearly 150 million years old."

Comments

Re:The ass casts the deciding vote

[ArcherB]

After about two seconds more research, I found that the condition is called Polycephaly:

Again, from Wiki. Copied and pasted to save you guys a click:

Polycephaly is the condition of having more than one head. By far the most common use is in relation to the anatomical head, though the word has also been used for other meanings of "head". The term is derived from the stems poly- meaning 'many' and kephal- meaning "head", and encompasses bicephaly and dicephaly (both referring to two-headedness). A variation is an animal born with two faces on a single head, a condition known as diprosopus. In medical terms these are all congenital cephalic disorders.

There are many occurrences of multi-headed animals, in real life as well as in mythology. Many fantasy universes contain races of creatures with multiple heads. In heraldry and vexillology, the double-headed eagle is a common symbol, though no such animal is known to have ever existed.

Bicephalic animals are the only type of multi-headed creatures seen in the real world and form by the same process as conjoined twins: the zygote begins to split but fails to completely separate. One extreme example of this is the condition of craniopagus parasiticus, whereby a fully developed body has a parasitic twin head joined at the skull.

Re:Latin name?

[aeschenkarnos]

Things only get Latin names if they're new species. This is a malformation that afflicts an individual member of a species that may or may not already be known. It certainly deserves an individual name (like the Australopithecus "Lucy"), and Zaphod is a good choice.

beeb article and questions

[gsn]

The beebs article has slightly more details and a picture of the actual fossil and a two headed snake.

http://news.bbc.co.uk/1/hi/sci/tech/6195345.stm

I'm not a biologist so does anyone know if the second head is fully functional? I'd have thought there'd be serious blood flow issues and it'd be unlikely for these animals to live very long but the snake at the bottom of the article doesn't look young. Does it act as a redundant system used only if the primary one fails or do they actually process stimuli from both heads? What happens if the stimuli are conflicting? Can someone point me towards anything on decesion making in these creatures or are they just not enough to study this. The beeb article says something vague about the condition being due to damage to the embryo possibly. What sort of damage? and how accepted is this?

Re:The ass casts the deciding vote

[networkBoy]

Without hitting the ID crap.
We often refer to mother nature "experimenting" with evolution. We here all know* that there is no ID in the experiment part of the statement, it is more a euphamism for some random mutation that may or may not stick. To that end the only intelligent thing about having your brain in your head is the bandwith available for visual and auditory perception and processing. I'd venture to say a brain in the chest cavity would make a hell of a lot more sense and invest in faster nerves for the ears and eyes, except that until recently if you lost your ears and eyes you were effectively dead anyway. Besides we all know the world was created last Thursday with all our engrams pre-programmed :-)

-nB

* even the trolls who refuse to acknowledge they know

Re:prolly a fake

[krayzkrok]

Everyone seems to be missing the point of this discovery (including most news agencies who think it's a cool story). Bifurcation of the head is a pretty common genetic abnormality in a number of vertebrates, but especially reptiles because eggs are exposed to a wider range of temperature extremes. High temperatures during incubation, particularly early in incubation, very often lead to genetic abnormalities. A "hot" crocodile or turtle nest, for example, will give you a lot of dead, deformed embryos including those with two tails, no jaws, two heads, and any other number of strange mutations. It's exceptionally rare for one to survive past hatching, but it has happened.

So basically these guys have discovered a fossilised embryo that was deformed during incubation, not a two-headed monster that terrorised the Cretaceous. It's neat to find one, but it's not a particularly novel discovery IMO.

Re:The ass casts the deciding vote

[vtcodger]

***If it made more "sense" to have the brain in the chest, we would have brains in our chests. It's just pointless to argue with mother nature when it comes to design. You can probably point to some kinks that specific species are still working out, but anything this universal is so damn near optimal that it's awe-inspiring.***

Mother nature doesn't necessarily come up with optimal designs, just non-lethal ones. "Tradition" has a lot of influence. In the case of heads and brains, our (hypothetical) bilateran ancestor probably was a segmented animal with a tendancy to merge the segments at one end into a specialized structure with things like eyes, mouth's et al slapped together from pre-existing structures. As a result, chordates, arthropods, mollusks, and various kinds of "worms" all have their heads on one end of the body.

At least that's what most people think is the reason for the architecture shared by many (not all) phyla. The fossil evidence from the time period where the various phyla probably diverged is scant and not entirely helpful.

Yes, if there were an enormous advantage to locating the brain in the torso, it'd probably be there. But if the advantage is small, and getting to that arrangement involves a number of steps with no particular advantage, it might very well never happen.

Re:The ass casts the deciding vote

[oni]

If it made more "sense" to have the brain in the chest, we would have brains in our chests. It's just pointless to argue with mother nature when it comes to design.

You're clearly very ignorant of how evolution works. Here's a quick counter example to disprove your "if it made more sense we'd have it" claim: The photoreceptor cells in your eye actually point backwards - toward the back wall of your eye. The nerve ending that transmits the captured light to the brain is on the front of the cell, and therefore has to be longer than strictly necessary (imagine a bunch of harddrives in a case. You would position the drives so that the cables all went out the back of the case. Now turn the drives around - you'll need longer cables and you'll have to route them along the side of each drive, taking up more room. Your eye is like that.)

So why does your eye have this curious and non-optimal design? Beats the hell out of me. It's just a quirk of evolution. Invertebrates evolved their eyes separately (convergent evolution), and they actually got the correct design. This is why an octopus' eye is so good. The cells are pointed the right way, so you can pack more of them together. It's a more efficient design. But you can't point to humans and say, "no no, don't argue with mother nature, if there was a better way we'd have it!" because that just isn't true. There is a better way. We don't have it. Octopuses have it. We got the shaft.

Evolution is random mutation and non-random selection. The best of the group survives. That in no way implies that the best is optimal. It was just the best available.