Explorornis
Encyclopedia
Explorornis is a genus
of Mesozoic
bird
s. It lived during the mid-late Turonian
stage, around 90 million years ago.
Unlinke many contemporary genera, which are only known from a handful of remains that cannot be compared among each other, Explorornis is known from a handful of coracoids which are similar enough to be at least preliminarily assigned to a single genus. Nonetheless, each of the named species
as well as the 2 unnamed ones are known by a single, damaged bone. They are all from the Bissekty Formation
of the Kyzyl Kum
, in present-day Uzbekistan
.
Explorornis means simply "discovered bird", from Latin
explōrō "to discover" and Ancient Greek
ornis (όρνις) "bird". The named species are honoring famous paleontologists: Lev Alexandrovich Nesov (1947–1995) and Cyril Alexander Walker.
E. walkeri (specimen PO
4825) was originally placed in Enantiornis
, because at the time of its description very little was known about Enantiornithes
diversity. With the description of the type species
E. nessovi (PO 4819), it became clear that E. walkeri was much closer to that bird than to the South America
n Enantiornis, which also makes far more sense considering biogeography
.
The unnamed specimens are distinct from these but each resembles one named species more than the other; PO 4818 seems closer to E. nessovi but is stouter than that bone, while PO 4817 appears more similar to E. walkeri.
These were all smallish birds, maybe 15–20 cm long in life, except E. walkeri which was probably more than 25 cm long.
Since only the coracoids are known, the phylogenetic position of these taxa is somewhat unresolved. They do resemble the more advanced Enantiornithes more than they do any other bird however. Confirmation of their placement with Euenantiornithes
would still require more material however.
In addition, E. walkeri and PO 4817 seem to be more apomorphic than the other two bones, judging from the little data available. The former have some similarities to taxa such as:
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...
of Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
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...
s. It lived during the mid-late Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
stage, around 90 million years ago.
Unlinke many contemporary genera, which are only known from a handful of remains that cannot be compared among each other, Explorornis is known from a handful of coracoids which are similar enough to be at least preliminarily assigned to a single genus. Nonetheless, each of the named 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...
as well as the 2 unnamed ones are known by a single, damaged bone. They are all from 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...
, in present-day 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....
.
Explorornis means simply "discovered bird", from Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
explōrō "to discover" and Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
ornis (όρνις) "bird". The named species are honoring famous paleontologists: Lev Alexandrovich Nesov (1947–1995) and Cyril Alexander Walker.
E. walkeri (specimen PO
Pô
-External links: Burkina Faso Ministry of Culture, Arts and Tourism's web site for this area...
4825) was originally placed in Enantiornis
Enantiornis
Enantiornis is a genus of predatory enantiornithine bird. The type and only currently accepted species E. leali is from Late Cretaceous rocks at El Brete, Argentina....
, because at the time of its description very little was known about Enantiornithes
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...
diversity. With the description of the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
E. nessovi (PO 4819), it became clear that E. walkeri was much closer to that bird than to the South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
n Enantiornis, which also makes far more sense considering biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
.
The unnamed specimens are distinct from these but each resembles one named species more than the other; PO 4818 seems closer to E. nessovi but is stouter than that bone, while PO 4817 appears more similar to E. walkeri.
These were all smallish birds, maybe 15–20 cm long in life, except E. walkeri which was probably more than 25 cm long.
Since only the coracoids are known, the phylogenetic position of these taxa is somewhat unresolved. They do resemble the more advanced Enantiornithes more than they do any other bird however. Confirmation of their placement with Euenantiornithes
Euenantiornithes
Euenantiornithes is a superorder of Cretaceous birds. They are considered to contain the more advanced taxa of the Enantiornithes, the dominant group of birds during the late Mesozoic...
would still require more material however.
In addition, E. walkeri and PO 4817 seem to be more apomorphic than the other two bones, judging from the little data available. The former have some similarities to taxa such as:
- GurilyniaGurilyniaGurilynia was a Genus of enantiornithine birds. One species is known, G. nessovi. It lived during the Maastrichtian stage of the Late Cretaceous period, between 70 and 65 mya. Gurilynia is known from fragmentary fossils found at the Gurilyn Tsav locality of the Nemegt Formation in south Gobi,...
, - HalimornisHalimornisHalimornis was an enantiornithine bird. It lived during the Late Cretaceous about 80 mya and is known from fossils found in the Mooreville Chalk Formation in Greene County, Alabama...
, - IncolornisIncolornisIncolornis is an extinct genus of basal birds from the Late Cretaceous . Remains have been found in the Bissekty Formation in Uzbekistan.It is only known from fragmentary coracoids...
and - LargirostrornisLargirostrornisLargirostrornis is a Genus of enantiornithine bird. One species is known, Largirostornis sexdentoris. It lived during the Early Cretaceous and is known from fossils found in the Jiufotang Formation in Liaoning province, People's Republic of China....
, and this might indicate that they do belong to a different as of yet unnamed genus after all.