Crassygyrinus

Looking like a monster stunt double from a star wars film, this was one of first tetrapods. It was also one of the ugliest, with a short deep skull, forelimbs that were useless for walking, and a face only a mother could love. But then again, this creature was not designed for aesthetic purposes or to lumber across land - this 1.5 metre monster was designed to terrorize the swampy Carboniferous waterways

Crassygyrinus ("thick tadpole") lived in what is today Scotland in the early Carboniferous era, one of few tetrapods that have been discovered in taht time period. The lack of tetrapod remains at this time is referred to as "Romers gap" Looking at the at the (weird) design of its skull and its body proportions, it has been suggested that it filled a niche in the coal swamps similar to the one that today the moray eels fulfill in the coral reefs of todays oceans. Namely, laze around in a dark corner for something to swim by, then grab it with a wicked set of jaws with two rows of teeth, one with a set of fangs.  The business end of this beast was a heavily reinforced skull, and the buttressed snout and kinetic inertial jaw mechanism would have given it a bone smashing bite.

We can be pretty sure that this beast was not going to go anywhere near the land - its forelimbs were tiny and attached near the skull, and it had back limbs just as useless for walking. We cannot be sure just what such small and seemingly almost useless limbs would be used for, but perhaps they were used to hold its position in amongst weeds, or in the act of mating, as did the primitive whale Basilosaurus.

 

Crassygyrinus was an offshoot of one of the earliest groups of tetrapods, and it shows similarities in its skull structure with a group called the osteolepiforms, which were the group from which tetrapods evolved. Crassigyrinus may have been an early offshoot of forms such as Icthyostega. As we only have one incomplete articulated skeleton of this animal (along with two other skulls), it is hard to say what group of early amphibians or stem tetrapods this animal is most closely related to.

It has had a notable appearance on the small screen, in the ITV documentary Prehistoric Park, where Nigel Marven goes hunting for live animals for a wildlife park. Sadly, Crassygyrinus did not make the grade for the park, with the spotlight on giant arthropods. In the coal swamps though, this was the top predator in the water.

Psudosculda laevis

The stomatopods are commonly known as mantis shrimps, but such a name does little justice to the abilities of these predators. The skeleton shrimps resemble mantids far more than the stomatopods, and in addition and with all due respect to the mantis, a stomatopod would eat it for breakfast no problem.

For example, it’s easy to replicate the vision of a mantis with a camera lens, but these predators can see things you can’t even imagine. Literally.

With what is reckoned to be up to ten different visual pigments, eyes split into two sections and stomatopod can do something that no other animal on the planet can do – it can perceive cross polarised light. This is for the purposes of display and to identify other members of its species, and also to identify the location of predators in the waters above. Evolution has allowed it to do this at the same time as it’s searching for its next hapless victim, thanks to a talent that no other creature possesses.

Optical elements in three parts of a stomatopods eye can focus on one point in space using the midband of the eye, in conjunction with the upper and lower hemisphere. In other words, a Mantis shrimp can see in trinocular vision. Very handy, when you have weapons that can shatter bones.

After the stomatopod has identified its victim, it brings into play its next party piece. Mother nature spoiled them somewhat. Not content with gifting them vision the envy of all other coral reef dwellers, she gave them weapons that would give every other animal on the sea floor nightmares.

Some stomatopods are “spearers”, impaling fish and other prey items on their front appendages. The first reaction of the prey item is generally flailing on the fearsome weapons.

Others are smashers, which use the appendages on the front limbs to smash apart the shells of mollusks, the exoskeletons of other crustaceans and even coral, if its victim tries to hide from the murderous weapons. In a faction of a blink of an eye due the mechanics of a release of tension accompanying the weapon, the club strikes with the force of a .22 bullet, and at a speed of 50 mph, all while underwater.

If the stomatopods punch does not land, the shockwave from the collapsing water almost certainly will, stunning the victim and allowing the fastest fists in the ocean another shot at the prey item.

You might think that the group is rather new, having such powerful weapons and such advanced sight, but the stomatopods are quite an ancient group, having been terrorising coral reefs since at least the Jurassic. The fossil member of the group here, Psudosculda laevis, is from the Cretaceous (95 million years ago) and like there predators today, this was a fearsome creature.

It had the raptorial appendages that are the trademark of the group, but we don’t know how advanced its vision was, or if it was monogamous like so many of today's extant members of the stomatopoda, but we can hazard a guess that this was not an animal to be messed with.

Welcome to the Strange Shrimp!

This blog will be all about creatures that are not around anymore, and that a part of me is sad about.
But the part that helps me get to sleep at night is most certainly not.

This blog will look at some of the most fearsome extinct creatures that we are lucky to know about, from all corners of the animal kingdom.