Nanantius
Encyclopedia
Nanantius eos
is the name of an Early Cretaceous
(Albian
, c. 100-112 mya) species
of bird
. It is the only described member of the genus
Nanantius at present; the supposed second species Nanantius valifanovi has turned out to be a synonym of Gobipteryx minuta. N. eos is known from two incomplete tibiotarsi
from the Toolebuc Formation
stratum, the first (Queensland Museum
F12992) found at Warra Station near Boulia, in Queensland
(Australia
). Other remains from Australia have also been placed into the genus Nanantius but not assigned to a species. Furthermore, there are some bones from the Late Cretaceous
, found in the Bissekty Formation
of the Kyzyl Kum
desert, Uzbekistan
, which belong either into Nanantius or a closely related genus; however, due to the date difference, they are almost certainly not N. eos in any case.
Initially, Nanantius eos was classified as an enanthiornithine
, a Cretaceous
group of primitive birds that did not survive the C-T mass extinction
. However, it is now known that the characters of the tibiotarsus are not sufficiently diagnostic to place a bird into the Enantiornithes. For example, the more modern genus Apsaravis
also possessed an "enantiornithine" tibiotarsus (Clarke & Norell, 2002). Thus, although an enantiornithine affinity of Nanantius is likely - these birds were the dominant avian group in the Early Cretaceous, and the tibiotarsus is very similar to the doubtlessly enantiornithine Gobipteryx -, this placement is not certain until more diagnostic material, such as the characteristic tarsometatarsi
, have been found.
N. eos was a small species, about the size of a Blackbird; it probably looked like a miniature gull with clawed wings and a neck and head more similar to a feathered theropod dinosaur
, but with a beak
. It is assumed to have fed on marine invertebrates and small fish; certainly, it lived on the coast of what was then the Eromanga Sea, a shallow subtropical arm of the Tethys Seaway
. That Nanantius were seabirds is evidenced by the fact that another tibiotarsus referrable to this genus, and quite possibly to N. eos itself, was found in the gut
of an ichthyosaur
(Kear et al., 2003).
is the name of an Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
(Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
, c. 100-112 mya) species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
. It is the only described member of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Nanantius at present; the supposed second species Nanantius valifanovi has turned out to be a synonym of Gobipteryx minuta. N. eos is known from two incomplete tibiotarsi
Tibiotarsus
The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia.A similar structure also occurred in the Mesozoic Heterodontosauridae...
from the Toolebuc Formation
Toolebuc Formation
The Toolebuc Formation is a geological formation in Queensland, Australia whose strata date back to the Early Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Vertebrate paleofauna:...
stratum, the first (Queensland Museum
Queensland Museum
The Queensland Museum is the state museum of Queensland. The museum currently operates four separate campuses; at South Brisbane, Ipswich, Toowoomba and Townsville.The museum is funded by the State Government of Queensland.-History:...
F12992) found at Warra Station near Boulia, in Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
(Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
). Other remains from Australia have also been placed into the genus Nanantius but not assigned to a species. Furthermore, there are some bones from the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
, found in the Bissekty Formation
Bissekty Formation
The Bissekty Formation is situated in the Kyzyl Kum desert of Uzbekistan, and dates from the late Cretaceous Period. Laid down in the early the Turonian to Coniacian stages, it is dated to about 90-85 ma .The Bissekty Formation is characterised by a mix of marine, brackish, freshwater, and...
of the Kyzyl Kum
Kyzyl Kum
The Kyzyl Kum , also called Qyzylqum, is the 11th largest desert in the world. Its name means Red Sand in Turkic languages. It is located in Central Asia in the doab between the rivers Amu Darya and Syr Darya, and is divided between Kazakhstan, Uzbekistan and Turkmenistan...
desert, Uzbekistan
Uzbekistan
Uzbekistan , officially the Republic of Uzbekistan is a doubly landlocked country in Central Asia and one of the six independent Turkic states. It shares borders with Kazakhstan to the west and to the north, Kyrgyzstan and Tajikistan to the east, and Afghanistan and Turkmenistan to the south....
, which belong either into Nanantius or a closely related genus; however, due to the date difference, they are almost certainly not N. eos in any case.
Initially, Nanantius eos was classified as an enanthiornithine
Enantiornithes
Enantiornithes is an extinct group of primitive birds. They were the most abundant and diverse avialans of the Mesozoic. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over 50 species of Enantiornithines have been named, but some...
, a Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
group of primitive birds that did not survive the C-T mass extinction
Cretaceous-Tertiary extinction event
The Cretaceous–Paleogene extinction event, formerly named and still commonly referred to as the Cretaceous-Tertiary extinction event, occurred approximately 65.5 million years ago at the end of the Maastrichtian age of the Cretaceous period. It was a large-scale mass extinction of animal and plant...
. However, it is now known that the characters of the tibiotarsus are not sufficiently diagnostic to place a bird into the Enantiornithes. For example, the more modern genus Apsaravis
Apsaravis
Apsaravis is a Mesozoic bird genus from the Late Cretaceous. The single known species, Apsaravis ukhaana, lived about 78 million years ago, in the Campanian age of the Cretaceous period. Its fossilized remains were found in the Camel's Humps sublocality of the Djadokhta Formation, at Ukhaa...
also possessed an "enantiornithine" tibiotarsus (Clarke & Norell, 2002). Thus, although an enantiornithine affinity of Nanantius is likely - these birds were the dominant avian group in the Early Cretaceous, and the tibiotarsus is very similar to the doubtlessly enantiornithine Gobipteryx -, this placement is not certain until more diagnostic material, such as the characteristic tarsometatarsi
Tarsometatarsus
The tarsometatarsus is a bone that is found in the lower leg of certain tetrapods, namely birds.It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsal and metatarsal bones...
, have been found.
N. eos was a small species, about the size of a Blackbird; it probably looked like a miniature gull with clawed wings and a neck and head more similar to a feathered theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
, but with a beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
. It is assumed to have fed on marine invertebrates and small fish; certainly, it lived on the coast of what was then the Eromanga Sea, a shallow subtropical arm of the Tethys Seaway
Tethys Ocean
The Tethys Ocean was an ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic era before the opening of the Indian Ocean.-Modern theory:...
. That Nanantius were seabirds is evidenced by the fact that another tibiotarsus referrable to this genus, and quite possibly to N. eos itself, was found in the gut
Gut (zoology)
In zoology, the gut, also known as the alimentary canal or alimentary tract, is a tube by which bilaterian animals transfer food to the digestion organs. In large bilaterians the gut generally also has an exit, the anus, by which the animal disposes of solid wastes...
of an ichthyosaur
Ichthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...
(Kear et al., 2003).