''Gettyia'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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 cla ...

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger 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 ''creta'', ...

of North America.

Description

''Gettyia'' is known from a single right tarsometatarsus. 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 raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predat ...

in particular utilize forceful flexion during their hunting behavior. Arboreal

parrots Parrots, also known as psittacines (), are birds of the roughly 398 species in 92 genera comprising the order Psittaciformes (), found mostly in tropical and subtropical regions. The order is subdivided into three superfamilies: the Psittacoide ...

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 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, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient sea ...

, 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 straight-line distance from the northernmost part of western Canada, to New Mexico ...

Classification

''Gettyia'' was originally named '' Avisaurus 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. Campani ...

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 and (million years ago), during Campanian (Late Cretaceous) time. It crops out to the east of the Rocky M ...

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 Avisaurids Campanian life Fossil taxa described in 2018 Late Cretaceous birds of North America Late Cretaceous dinosaurs of North America Prehistoric bird genera