Australia: The Land Where Time Began

A biography of the Australian continent 

Ptyctodontids

This placoderm group has some record in the New South Wales Early Devonian. The finds are not yet completely published. In appearance, the ptyctodontids look a bit like modern fish because of the greatly reduced armour. This armour was only on the top of the head and a short shield on the trunk. They had long, slim, scaleless bodies, with a narrow whip-like tail. The look very much like the ghost fish (chimaeroids or holocephalians).

They were mostly less than 20 cm and mostly marine. Their teeth, reinforced with dentine, were large plates which could shear and crush. A feature of the ptyctodontids was the possession of claspers, as in modern sharks and chimaeroids, though they were constructed differently, but it is possible they were used in the same way as modern claspers to aid in internal fertilisation. Maybe a case of convergent evolution.

The relationship of the ptyctodonts to other known groups is uncertain. They became much more diverse in the Devonian.

see Oldest Mother

Sources & Further reading

1. John A Long The Rise of Fishes - 500 Million years of Evolution, University of New South Wales Press, 1995

Fish