Patagopteryx
Patagopteryx, skeletal reconstruction
Patagopteryx is an extinct genus flightless birds of the Upper Cretaceous. The fossil remains of three specimens were found in the Bajo de la Carpa Formation in northwestern Patagonia (Neuquén ). The only way is Patagopteryx deferrariisi.
Features
Patagopteryx was about chickens tall, with strong hind legs and atrophied wings. The foot is pamprodactyl, all four toes pointing forward. The Phalanagenformel is 2-3-4-5.
The skeleton suggests that his ancestors were airworthy. The sternum is small and has no sternum ridge ( carina sterni ). Also the Carpometacarpus, a bone (ossa distalia carpal bones ) is formed with each other and with the proximal ends of the original three metacarpal bones ( metacarpals ) from the fusion of the distal carpal bones is small. Patagopteryx so is the oldest bird, for a secondary flightlessness is demonstrated.
His trunk vertebrae were from primitive procoelous (front concave, convex rear ) type, all other vertebrae were heterocoel (both ends concave), as is typical for modern birds. Ischium and pubis both point to the rear. The elongated bones of the species show distinct growth rings, which is typical for the Enantiornithes, but otherwise occurs with no further Cretaceous or modern bird group. Maybe he differed physiologically from modern birds, was not fully endothermic and had to spend part of the year in a sort of hibernation. He lived in a continental climate, which was characterized by large seasonal temperature fluctuations.
System
Patagopteryx was originally thought to be a primitive relatives of the ratites. Today, his position within the bird nomenclature is defined as isolated and he stands in its own family and order. The probable systematic position cladogram shows the following:
Archaeopterygidae
Enantiornithes
Patagopteryx
Vorona
Hesperornithiformes
Ichthyornithiformes
Neornithes ( extant birds)