The Rhamphorhynchoids-Page 2

One obvious difference between Rhamphorhynchoids and Pterodactyloids is the presence of a long tail in the Rhamphorhynchoids. The tail includes up to 40 vertebrae and was cross braced and stiffened by a system of longitudinal tendons. The function of the tail remains unclear: it certainly helped the animal steer once airborne but it may have also helped in counterbalancing the weight of the skull when the animal was on the ground.

As characterized by all pterosaurs, the wing membrane is stretched by an elongated fourth finger. The wrist bones are not fused and the phalanges are longer than the metacarpals. In the shoulder, the clavicle was not fused to the sacral vertebrae as in the larger and more advanced Pterodactyloids. A fused clavicle is not needed in Rhamphorhynchoids because of their smaller size and hence flight stresses were lessened.

Examples of Rhamphorhynchoids
1) Dimorphodon
2) Rhamporyhynchus
3) Sordes
4) Anurognathus

© Patrick Lyons 1998.