A Dinosaur In Your Home? Unearthing The Ancestry Of Living Reptiles

So are reptiles the direct descendants of dinosaurs? They may look like them, but be prepared to be surprised as james brereton msc reveals the truth!

Many modern reptiles seen in collections today can show a striking resemblance to a more primitive group of animals – the dinosaurs. From the armoured horned lizard (Phryonosoma platyrhinos) to the raptoresque bearded dragon (Pogona vitticeps), dinosaurs and reptiles alike both fascinate us. Despite their perceived similarity in appearance however, many reptiles share only a distant genetic lineage with the prehistoric ‘terror lizards’, whereas others have a much closer relationship with the dinosaur lineage.

Indeed, some of the closest-living relatives of the dinosaur are surprising. This article will reveal the relationships between reptiles and their larger, extinct cousins (twice removed), as well as explaining how these relationships affect the biology and behaviour of our modern day charges.

Emergence of reptiles

Reptiles are not directly descended from dinosaurs. The first reptiles evolved from what was originally an amphibious ancestor, as early as 310 to 320 million years ago. The changes required to transform an amphibian into a reptile occurred gradually over the course of millions of years. Confined to wetlands and freshwater, amphibians were unable to take advantage of the scrubland, forests and desert habitats available.

The changes in amphibian biology that ultimately led to reptiles reflect essential adaptations toward conserving water, providing an ability to colonise terrestrial habitats in which water is relatively scarce. The characteristic amphibian skin, so important in absorbing oxygen, became replaced with a dry, scaled skin which is much more effective in retaining water. The moist eggs of amphibians, which need to be deposited in water or a high humidity environment, became encased in a hard shell, meaning that the entire reptile life cycle could occur outside of water.