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Description
Archaeopteryx. Ambulacetus. Australopithecus. Apart from alliteration, these creature share something in common. They are some of the most famous 'transitional' fossil forms known. That phrase is problematic for a lot of reasons, so just take it to mean animals that share features of earlier, more basal members of a clade, and later more-derived forms. A new one of these important creatures was published about a month ago - Cartorhynchus. It's a very early member of the Ichthyosaur group of marine reptiles. While later forms are extremely well adapted to an exclusively oceanic lifestyle, it's long been a mystery as to what kind of amphibious creatures they evolved from. Cartorhynchus is not a direct ancestor to later Ichthyosaurs, but it does reveal something about what those ancestors were probably like.

But in reality, transitional forms don't think of themselves as transitional. They go on about their lives, totally unaware of the major implications of their new, novel features. So here we see these three Cartorhynchus, going on about their business in this shallow sea water, playing in the surf and looking for something nice to suck up in their shortened snouts. They are blissfully unaware that they have taken some of the first steps down a line that will lead to a fascinating group of extraordinary reptiles. Hell, they're so preoccupied with their lives, they haven't even seen the hybodoid shark looming in the nearby gloom....

Description
Archaeopteryx. Ambulacetus. Australopithecus. Apart from alliteration, these creature share something in common. They are some of the most famous 'transitional' fossil forms known. That phrase is problematic for a lot of reasons, so just take it to mean animals that share features of earlier, more basal members of a clade, and later more-derived forms. A new one of these important creatures was published about a month ago - Cartorhynchus. It's a very early member of the Ichthyosaur group of marine reptiles. While later forms are extremely well adapted to an exclusively oceanic lifestyle, it's long been a mystery as to what kind of amphibious creatures they evolved from. Cartorhynchus is not a direct ancestor to later Ichthyosaurs, but it does reveal something about what those ancestors were probably like.

But in reality, transitional forms don't think of themselves as transitional. They go on about their lives, totally unaware of the major implications of their new, novel features. So here we see these three Cartorhynchus, going on about their business in this shallow sea water, playing in the surf and looking for something nice to suck up in their shortened snouts. They are blissfully unaware that they have taken some of the first steps down a line that will lead to a fascinating group of extraordinary reptiles. Hell, they're so preoccupied with their lives, they haven't even seen the hybodoid shark looming in the nearby gloom....