Polycephaly is the condition of having more than one head. Two-headed animals (called bicephalic or dicephalic) and three-headed (tricephalic) animals are the only type of multi-headed creatures seen in the real world, and form by the same process as conjoined twins from monozygotic twin embryos.
While two headed snakes are rare, they do occur in both the wild and in captivity at a rate of about 1 in 10,000 births. Most wild polycephalic snakes do not live long, but some captive individuals do. A two-headed black rat snake with separate throats and stomachs survived for 20 years.
(Sources: x x x x x x x x)
Why does this seem to happen to snakes so often compared to other animals? I mean, you don’t see this happen to dogs or cats very often but snake embryos seem almost eager to mix it up every once in a while and pull a two-for-one deal in the head department.
The consensus seems to be that polycephaly occurs more often in reptiles than other animals, but the why of it, as far as I could find out, is relatively unknown. Polycephalic animals appear so infrequently and they survive for such a short time that scientists just have not been able to study them sufficiently. If anyone can find more information about why it happens more often in reptiles, feel free to chime in. In the meantime, enjoy these two-headed lizards and turtles:
Can you imagine the arguments!
One thought real quick: two-headed dinosaurs
oh my god i will lose my fuckin mind the day that fossil is found
@magicturtle two headed dinosaurs seems like something you’d be down for.
Rawr YEAH!
I think I misunderstood the assignment.
Um not to put a dampener on the idea of two headed dinos but aren’t dinosaurs closer to birds and birds most likely don’t have two heads.
Birds are reptiles! That sounds insane, but let me explain. Biologists use a system to classify animals called the phylogenetic system, which means animals are grouped together based on their ancestry. In this way, birds are reptiles because they’re more closely related to reptiles than anything else, crocodiles in particular. In fact, crocodiles are more closely related to birds than they are to lizards. The first groups of reptiles evolved about 300 million years ago. About 40 million years later, a group of reptiles called therapsids branched off, which eventually became modern mammals. Other groups of reptiles split off over the next 120 million years, one branch being the dinosaurs. These dinosaurs were only distantly related to modern snakes, lizards, and turtles, groups that had split off at different times. But 65 million years ago there was a massive extinction event, and all dinosaurs were killed except for a single group of feathered dinosaurs. These evolved over the next 65 million years into modern birds. So birds are dinosaurs, and dinosaurs were reptiles, and thus birds are reptiles.
Additionally, there were two-headed dinosaurs! Well, at least one. That we know of. I can’t add the picture bc mobile but here’s a link: http://news.nationalgeographic.com/news/2006/12/061226-two-heads_2.html
#somebody not on mobile add the picture please?
here you go
however, the above mentioned and pictured fossil was not a dinosaur - just an aquatic reptile from the Cretaceous period - which is still badass! also this is one of the coolest threads ever.
Excellent additions!
A point I forgot to mention in my birds-are-reptiles ramblings…two-headed birds are definitely a (rare) thing. This bird with two heads and three beaks was found in Massachusetts. (x)
This is the true reason I got involved in Tumblr. Bring back these posts!!
