Sunday, October 28, 2007

Lysorophian attacks!

The mighty Dimetrodon was the biggest, scariest, most massive thing to walk the Permian, the size of a modern-day tiger. But what teeny-tiny little creatures scurried around between its toes?

Look at any environment today, and you'll see that most things are small - like the hundreds of species of frogs that inhabit the rainforest or the hundreds of thousands of species of beetles living all around the world. And while it's easy to be wowed by the biggest and the meanest - it's often the smallest of the small that have the most to tell us about what life was like when they were alive.

Though the small critters have the advantage of numbers - it's the big guys that are most likely to stick around long enough to get fossilized. Small bodies are easy prey for scavengers and tiny skeletons often don't have what it takes to survive the elements long enough to be buried and preserved.

And so our knowledge is skewed to the super-sized - the Megalodons and Titanosaurs. But the pint-sized are much more sensitive to their environment - like the frogs or salamanders of today - and can tell us much more about conditions in a given era.

For this reason, the HMNS dig team has been thrilled to find many fossilized Lysorophians - which grew to only about a foot long - at the site.

(c) Robert T. Bakker

Though small, this species was armed to the teeth:

"The jaw bones were thick for such a little animal and carried strong, slightly curved fangs...Most astonishing was the body form...The torso went on and on and on. And on, a total of nearly a hundred vertebrae, so the distance from neck to hips was thirty times the head length. The ribs were long, curved and of exceptional thickness and strength. In other words, the design was emphatically like a chunky snake’s."

Though they resemble thick-bodied vipers, Lyserophians are in fact amphibians - evident from four stout bones in their throats that supported gills, something no reptile ever has. And they used this as a weapon, too:

"Gill slits aren’t just for breathing in the water. They’re for hydraulic ambushes."

In theory, the Lysorophian would have explosively widened it's mouth, sucking in water and prey, clamped the jaws shut to impale the prey, and then sent the water rushing out of the gills. In addition:

"The jawbones of lysorophians were stouter than what most amphibians have today, so the killing bite must have been stronger...Plus – the immense strength of the ribcage could have pinned prey within the body coils."

Permian small(er) fry had much to fear from the Lysorophian. But what, in turn, killed them in such numbers in the Texas Red Beds? Hundreds have been found, each of similar size, and all curled into a ball, with the head tucked between the torso.

As it turns out, drought doesn't care how strong your jaws are. And in the Late Carboniferous-Early Permian, the world was hit with one of the greatest killing-drought cycles of all time. As an amphibian, Lysorophian needed water - and lots of it. To survive the drought, it learned to hibernate.

"The rainy season would mean a flush of greenery and prey everywhere. Lysorophians ate their fill and grew fast, courted mates and reproduced. Then, when drought returned, the entire generation went down into their burrows together...The Amphiuma of today’s ponds curl around their eggs to keep them moist and safe. Maybe the bomb-shelters of the Sleeping Serpents were maternity wards."

On the HMNS site in Seymour, the team has found five complete skeletons, in the same grouped pattern. The team has also found Gnathorhiza (Permian Lungfish) - also burrowers - nearby. Dr. Bakker theorizes that "Perhaps they were waiting for spring rains that never came." Like the amphibians of today, they are important environmental indicators - whenever a large number are found together, you know that something happened to kill them off.

(Quotes and information excerpted from The Sleeping Serpents of the Texas Redbeds by Dr. Robert T. Bakker.)

1 comment:

Alfred said...

Thank you for the article, very worthwhile material.
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