Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

What does anapsid mean?

Melissa Kaplan


A long time ago and far, far away, ancestors of today's amphibians were dependent upon water or very damp areas in which to lay their eggs. Their eggs, fertilized cells covered by a moist, gelatinous mass, had to be kept wet or damp in order to not dry out before they hatched. As with today's amphibians, egg masses are laid in water, in very damp burrows or the natural rain-filled cups formed by some plants, or encased in a frothy mass that hardens to a shell-like consistency on the outside, maintaining the necessary humidity inside.

This was all very well and nice, but it did rather limit the ability of amphibians to travel away from water and damp areas. This tended to limit species to, well, relatively limited areas. In the late Devonian period, a new egg appeared on the scene: the amniotic egg. These eggs featured a tough outer layer that prevented the eggs from drying out. This meant that the amniotes (the animals who began forming amniotic eggs) were not restricted to wet regions. Instead, they were able to radiate out, settling into new habitats.

The earliest amniotes thus far found date from the Carboniferous. By the end of this era, amniotes had split into three groups: the anapsids, the diapsids, and synapsids*. The anapsids were the earliest of reptiles. The diapsids are believed to have eventually evolved into reptiles, birds and dinosaurs, and the synapsids into mammals.

The different -sid classifications are based on the number of openings in the skull besides the eye sockets. Anapsids have no other openings, synapsids have one, and diapsids two. Modern reptiles are, for the most, diapsids, with the exception being the chelonians (turtles and tortoises), who are anapsids. Interested in learning more about anapsids, synapsids, and diapsids? Check out the University of California, Berkeley webpages on anapsida, synapsida, and diapsida.

So, when trying to come up with an easily pronounced and spelled name for my domain, I decided upon anapsid. They were the earliest of reptiles, and in a strangely twisted logical way, the idea of being "first" fits with my belief that one should start researching reptiles and reptile care long before actually acquiring one.

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