Hesperornithes
Skeletal reconstruction of Hesperornis regalis
- North America: Kansas ( Niobrara Chalk ) Saskatchewan ( Judith River Formation ), Alaska
- Europe: UK, Sweden, Ukraine
- Asia: Kazakhstan, Russia, Mongolia
- Antarctica
The Hesperornithiformes are a group dentate flightless diving birds, whose fossils occur in sedimentary rocks of the Cretaceous of North America, Eurasia and of Antarctica.
The oldest of the known genera is Enaliornis from the Lower Cretaceous ( Albian ) of the Cambridge Greensand near Cambridge. The majority of the species lived in the Upper Cretaceous. Hesperornis is detected in marine deposits of western North America from the Coniacian to the Campanian and thus the longest-lived of the previously discovered species of Hesperornithiformes. In the Maastrichtian, at the end of the Cretaceous, died from the group.
As diving birds that swam with the legs, Enaliornis, Hesperornis and Baptornis possessed rudimentary wings. In Hesperornis the forelimbs were only of a splintartigen upper arm. Some smaller species of Hesperornithiformes which reached the size of cormorants were possibly still airworthy. On land hesperornithiforme birds are likely similar to the extant loons have been rather awkward. There are finds from estuarine and continental deposits, demonstrating that they inhabited not only marine but also other aquatic habitats.
The largest previously known representatives are members of the 1999 described species Canadaga arctica. They could reach lengths of over 1.5 meters.
Relationships
The representatives of the Hesperornithiformes had just as many most other birds of the Cretaceous in the beak rows of simple, sharp teeth, which were, for example, suitable for gripping fish prey. Marsh described in 1880 Ichthyornis and Hesperornis from the Niobrara Formation as members of the group Odontornithes ( "Chalk tooth Birds "). It was found, however, that the gull -like Ichthyornithiformes are more closely related to modern birds ( Neornithes ) than with the Hesperornithiformes.
? Oviraptorosaurier (not too loud birds Fastovsky and Weishampel 2005)
Patagopteryx
Vorona
Enaliornithidae
Baptornithidae
Hesperornithidae
Ichthyornithiformes
Neornithes ( " Aves " by Fastovsky and Weishampel 2005)
Archaeopterygidae
( Simplified cladogram based on Zhou 2004, within the Hesperornithiformes by Martin in 1984, see Feduccia 1999)
Families
- Baptornithidae
- Enaliornithidae
- Hesperornithidae