''Alpkarakush'' 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 of

metriacanthosaurid Metriacanthosauridae (Greek for "moderately-spined lizards") is an extinct family of allosauroid theropod dinosaurs that lived in Europe and Asia from the Middle Jurassic to the Early Cretaceous. The family is split into two subgroups: Metriacant ...

theropod dinosaurs from the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

Balabansai Formation The Balabansai Formation (sometimes transcribed Balabansay, also known as Balabansai Svita) is a geological formation in Kazakhstan, Kyrgyzstan and Uzbekistan whose strata date back to the Bathonian and Callovian stages of the Middle Jurassic. ...

of Kyrgyzstan. The genus contains a single species, ''A. kyrgyzicus'', known from a partial skeleton.

Discovery and naming

The ''Alpkarakush'' fossil material was discovered in sediments of the

('FTU-1' locality) in the Uurusai Valley near Tashkumyr in Jalal-Abad Oblast of Kyrgyzstan. Initial fieldwork at the locality was conducted in 2005 and 2006, during which two partial theropod skeletons were found. Further excavations in 2014 recovered additional material, followed by later work in 2016 and 2017. A 2023 expedition revisited the site and found even more material, including teeth and isolated bones. At least two individual animals are represented by the recovered bones, both of which are assigned to ''Alpkarakush''. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen consists of skull bones (both

postorbital The ''postorbital'' is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra. In some ve ...

s and a

quadratojugal The quadratojugal is a skull bone present in many vertebrates, including some living reptiles and amphibians. Anatomy and function In animals with a quadratojugal bone, it is typically found connected to the jugal (cheek) bone from the front and ...

), several partial

dorsal vertebrae In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebra (anatomy), vertebrae of intermediate size between the ce ...

and five

sacral vertebrae The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, ...

, some

rib In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...

s, a manual

phalanx The phalanx (: phalanxes or phalanges) was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar polearms tightly packed together. The term is particularly used t ...

and

ungual An ungual (from Latin ''unguis'', i.e. ''nail'') is a highly modified distal toe bone which ends in a hoof, claw, or nail. Elephants and ungulates have ungual phalanges, as did the sauropod Sauropoda (), whose members are known as sauropods (; ...

(digit bone and claw), much of the

pelvic girdle The hip bone (os coxae, innominate bone, pelvic bone or coxal bone) is a large flat bone, constricted in the center and expanded above and below. In some vertebrates (including humans before puberty) it is composed of three parts: the Ilium (bone) ...

, and most of the hindlimbs (

femora The femur (; : femurs or femora ), or thigh bone is the only bone in the thigh — the region of the lower limb between the hip and the knee. In many four-legged animals the femur is the upper bone of the hindleg. The top of the femur fits in ...

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

e, left

fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. ...

, astragalo calcanea, a left tarsal,

metatarsals The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges (toes). Lacking individual names, the metatarsal bones are nu ...

, a pedal phalanx, and two pedal unguals). The

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype (biology), isotype ...

specimen belongs to a smaller individual and consists of a partial pelvic girdle and the right tibia. At least seven isolated teeth and a

furcula The (Latin for "little fork"; : furculae) or wishbone is a forked bone found in most birds and some species of non-avian dinosaurs, and is either an interclavicle or formed by the fusion of the two clavicles. In birds, its primary function is ...

were found nearby and assigned to ''Alpkarakush'', although the association of some of the teeth with this taxon is only tentative. All of the fossil material is housed at the Institute of Geology's Paleontological Collection, associated with the Kyrgyz National Academy of Sciences. In 2024, Rauhut et al. described ''Alpkarakush kyrgyzicus'' as a new genus and species of metriacanthosaurid theropod based on these fossil remains. The generic name, ''Alpkarakush'' is the name of a mythical powerful bird from the

Epic of Manas The ''Epic of Manas'' is a lengthy and traditional epic poem of the Kyrgyz people of East and Central Asia. Versions of the poem which date to the 19th century contain historical events of the 8th century, though Kyrgyz tradition holds it to be ...

. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

, ''kyrgyzicus'', references the discovery of the taxon in the Kyrgyz Republic.

Description

As a metriacanthosaurid theropod, ''Alpkarakush'' is a relatively large predator characterized by a high, arched skull and generally slender hindlimbs. These taxa have a pronounced orbital brow—a decorative structure over the eye— which is especially apparent and rugose in ''Alpkarakush''. ''Alpkarakush'' has an estimated body length of . Based on growth marks observed in the femur via

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...

, Rauhut et al. determined that the holotype (the larger of the two known specimens) was at least 17 years old when it died, and was likely still growing slowly. The smaller paratype was much younger when it died, either a large juvenile or possibly a small subadult.

Classification

In their

phylogenetic analyses In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organ ...

, Rauhut et al. (2024) recovered as a basal member of the

clade Metriacanthosaurinae. Their results are displayed in the

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below:

References

External links

YouTube video: "The discovery of the predatory dinosaur ''Alpkarakush''"
{{Taxonbar, from1=Q129426802, from2=Q129426817 Metriacanthosauridae Dinosaur genera Callovian dinosaurs Dinosaurs of Asia Fossil taxa described in 2024