Tingmiatornis
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''Tingmiatornis'' (meaning "bird that flies") is a genus of flighted and possibly diving
ornithuran Ornithurae (meaning "bird tails" in Greek) is a natural group that includes modern birds and their very close relatives such as the ichthyornithines and the hesperornithines. This clade is defined in the ''PhyloCode'' by Juan Benito and collea ...
dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...
from the High Arctic of
Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
. The genus contains a single species, ''T. arctica'', described in 2016, which lived during the
Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...
epoch of the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
.


Description

Given the small number of bones that are referrable to ''Tingmiatornis'', it is difficult to infer much about the animal. However, the thickness of the
cortical bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...
(on average, ) and the relative length of the
humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...
suggest that it was apparently capable of flight and likely also diving, similar to the possible
hesperornithine Hesperornithes is an extinct and highly specialized group of aquatic avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genera such as ''Hesperorn ...
'' Pasquiaornis''. ''Tingmiatornis'' can be differentiated from the latter by numerous traits including larger size, a more globe-shaped dorsal condyle on the humerus, an
olecranon process The olecranon (, ), is a large, thick, curved bony process on the proximal, posterior end of the ulna. It forms the protruding part of the elbow and is opposite to the cubital fossa or elbow pit (trochlear notch). The olecranon serves as a lever ...
of the
ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...
that does not project outward as strongly, as well as a smaller bicipital tubercle of the ulna. ''Tingmiatornis'' also differs from ''
Ichthyornis ''Ichthyornis'' (meaning "fish bird", after its fish-like vertebrae) is an extinct genus of toothy seabird-like ornithuran from the late Cretaceous period of North America. Its fossil remains are known from the chalks of Alberta, Alabama, Kansa ...
'' in the following ways: the
head of the humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists o ...
is more rounded and projects further downwards; the deltopectoral crest of the humerus is narrower and curves slightly forwards; the secondary pneumotricipital fossa of the humerus is deeper; and the expansion of the humerus known as the bicipital crest is longer, with a slightly convex bottom edge that transitions smoothly into the rest of the humerus rather than being hatchet-shaped.


Discovery and naming

The remains of ''Tingmiatornis'' were found on
Axel Heiberg Island Axel Heiberg Island (, ) is an uninhabited island in the Qikiqtaaluk Region, Nunavut, Canada. Located in the Arctic Ocean, it is the 32nd largest island in the world and Canada's seventh largest island. According to Statistics Canada, it ha ...
in the High Arctic of
Nunavut Nunavut is the largest and northernmost Provinces and territories of Canada#Territories, territory of Canada. It was separated officially from the Northwest Territories on April 1, 1999, via the ''Nunavut Act'' and the Nunavut Land Claims Agr ...
,
Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
, in an as-of-yet unnamed -thick layer of
Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...
rock between the
Kanguk Formation The Kanguk Formation is a geological formation in the Northwest Territories and Nunavut, Canada whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampel, David B ...
and the Strand Fiord Formation. Radiometric dating places the age of these rocks at 92 Mya. The type specimen consists of a left humerus labelled with the specimen number NUFV 1960, kept in the Nunavut Fossil Vertebrate Collection of the
Canadian Museum of Nature The Canadian Museum of Nature (; CMN) is a national museums of Canada, national natural history museum based in Canada's National Capital Region (Canada), National Capital Region. The museum's exhibitions and public programs are housed in the Vi ...
. Other specimens referred to ''Tingmiatornis'' consist of a partial humerus (UR 00.200, stored at the
University of Rochester The University of Rochester is a private university, private research university in Rochester, New York, United States. It was founded in 1850 and moved into its current campus, next to the Genesee River in 1930. With approximately 30,000 full ...
) and ulna (NUFV 1838). The genus name of ''Tingmiatornis'' incorporates the
Inuktitut Inuktitut ( ; , Inuktitut syllabics, syllabics ), also known as Eastern Canadian Inuktitut, is one of the principal Inuit languages of Canada. It is spoken in all areas north of the North American tree line, including parts of the provinces of ...
word "Tingmiat", which means "those that fly". The species name, ''arctica'', refers to the specimens being discovered in the High Arctic.


Paleoecology

A number of other vertebrates are known alongside ''Tingmiatornis'' from the locality on
Axel Heiberg Island Axel Heiberg Island (, ) is an uninhabited island in the Qikiqtaaluk Region, Nunavut, Canada. Located in the Arctic Ocean, it is the 32nd largest island in the world and Canada's seventh largest island. According to Statistics Canada, it ha ...
, including champsosaurs that measured in length; fish including
gar Gars are an ancient group of ray-finned fish in the family Lepisosteidae. They comprise seven living species of fish in two genera that inhabit fresh, brackish, and occasionally marine waters of eastern North America, Central America and Cuba ...
,
bowfin The ruddy bowfin (''Amia calva'') is a ray-finned fish native to North America. Common names include mudfish, mud pike, dogfish, grindle, grinnel, swamp trout, and choupique. It is regarded as a relict, being one of only two surviving species ...
s, members of the extinct
Vidalamiinae The Amiidae are a family of basal (phylogenetics), basal ray-finned fishes. The bowfin and the eyespot bowfin (''Amia ocellicauda'') are the only two species to survive today, although additional species in all four subfamilies of Amiidae are kno ...
, and indeterminate
teleost Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...
s; turtles, including ''
Aurorachelys ''Aurorachelys'' is an extinct genus of turtle which existed in Canada (Nunavut) during the late Cretaceous period, containing a single species, ''A. gaffneyi''. (Popular presentation of the above report) The type specimen is UR 06.085 at the Un ...
'', '' Borealochelys'', indeterminate eucryptodires, and indeterminate trionychids; and juvenile elasmosaurs, known from teeth. During the
Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...
, the area would have been a large, freshwater to brackish bay situated at approximately 71° paleolatitude. This habitat, which had a mean temperature of approximately 14 °C, would have been an ideal nesting ground for ''Tingmiatornis'', although no eggs or nests have been found at the locality to date. The bowfins that swam in the surrounding water, which likely measured in length, may have competed with ''Tingmiatornis'' for smaller fish, if the latter was a diving animal. ''Tingmiatornis'' may also have fished at night, much like the modern
Western grebe The western grebe (''Aechmophorus occidentalis'') is a species in the grebe family of water birds. Folk names include "dabchick", "swan grebe" and "swan-necked grebe". Western grebe fossils from the Late Pleistocene of southwest North America we ...
; at this latitude, it would have experienced approximately two months of continuous darkness per year. During the Late Cretaceous, high latitudes appeared to have been dominated by ornithurines as opposed to the more basal
enantiornithines 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 ...
. This may be due to ornithurines exploiting more aquatic niches or having higher growth rates in highly seasonal climates; the latter likely did not apply as strongly to ''Tingmiatornis'' due to the warm local climate.


References

{{Taxonbar, from=Q28050733 Avialae Turonian life Late Cretaceous dinosaurs of North America Fossils of Canada Paleontology in Nunavut Fossil taxa described in 2016