''Gettyia'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of avisaurid

enantiornithean The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cl ...

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

Description

''Gettyia'' is known from a single right

tarsometatarsus The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bird bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) a ...

. This bone was similar to that of other North American avisaurids such as ''Avisaurus'' and ''Mirarce'', but it was much smaller. The

second metatarsal The second metatarsal bone is a long bone in the foot. It is the longest of the metatarsal bones, being prolonged backward and held firmly into the recess formed by the three cuneiform bones. The second metatarsal forms joints with the second pr ...

had a tubercule (knob-like structure) on its front edge, which likely connected to the ''tibialis cranialis'' muscle which flexes the ankle. Other avisaurids typically had this tubercule located midway on the shaft of the metatarsal, or closer to the ankle than the toes. ''Gettyia'', on the other hand, had its ''tibialis cranialis'' tubercule located more than halfway down the shaft. The third and fourth metatarsals are more extensively fused than in other avisaurids, as fusion occurs not only near the ankle, but also near the toes.

Paleobiology

The more distally placed ''tibialis cranialis'' tubercule of ''Gettyia'' suggests that it had a more specialized lifestyle compared to other avisaurids. Zeffer & Norberg (2003) have found that living birds with a distally placed ''tibialis cranialis'' tubercules were biomechanically inclined to emphasize force of flexion, rather than speed.

Birds of prey Birds of prey or predatory birds, also known as (although not the same as) raptors, are hypercarnivorous bird species that actively predation, hunt and feed on other vertebrates (mainly mammals, reptiles and smaller birds). In addition to speed ...

in particular utilize forceful flexion during their hunting behavior. Arboreal

parrots Parrots (Psittaciformes), also known as psittacines (), are birds with a strong curved beak, upright stance, and clawed feet. They are classified in four families that contain roughly 410 species in 101 genus (biology), genera, found mostly in ...

and other climbing birds also make use of forceful flexion to obtain stability while foraging or hanging from tree branches. More terrestrial birds typically need more speed and less force, to assist locomotion like walking and hopping.

Paleoecology

''Gettyia'' is known from the

humid Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depe ...

low-lying swamps, lakes, and river basins of the western shore of the

Western Interior Seaway The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, or the Western Interior Sea) was a large inland sea (geology), inland sea that existed roughly over the present-day Great Plains of ...

, and from the much more arid uplands between that area and the Cordilleran Overthrust Belt which eventually formed the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in great-circle distance, straight-line distance from the northernmost part of Western Can ...

Classification

''Gettyia'' was originally named ''

Avisaurus ''Avisaurus'' (meaning "bird lizard") is a genus of enantiornithine avialan from the Late Cretaceous of North America. Discovery ''Avisaurus archibaldi'' was discovered in the Late Cretaceous Hell Creek Formation of North America (Maastrichtian, ...

gloriae'' by Varrichio and Chiappe (1995) for MOR 553E/6.19.91.64, a tarsometatarsus from the late

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

Upper

Two Medicine Formation The Two Medicine Formation is a geological formation, or rock body, in northwestern Montana and southern Alberta that was deposited between 82.4 Ma and 74.4 Ma, during Campanian (Late Cretaceous) time. It crops out to the east of the Rocky Mountai ...

of Glacier County, Montana, USA. The species name honors Gloria Siebrecht, a volunteer fossil collector at the Museum of the Rockies who discovered the specimen. A new partial skeleton of an enantiornithean that would come to be known as '' Mirarce'' prompted Atterholt ''et al.'' (2018) to re-evaluate avisaurid taxonomy. They found that ''Mirarce'' was intermediate between "''Avisaurus" gloriae'' and ''Avisaurus archibaldi'', showing that the two "''Avisaurus''" species were not actually members of a single monophyletic genus. To solve this problem, they created the genus name ''Gettyia'' for ''Avisaurus gloriae'', honoring the late Mike Getty.

References

{{Taxonbar, from=Q58680607 Avisauridae Campanian life Fossil taxa described in 2018 Late Cretaceous birds of North America Late Cretaceous dinosaurs of North America Prehistoric bird genera