''Cardiocorax'' 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 ...

elasmosaurid Elasmosauridae is an extinct family of plesiosaurs, often called elasmosaurs. They had the longest necks of the plesiosaurs and existed from the Hauterivian to the Maastrichtian stages of the Cretaceous, and represented one of the two groups of ...

known 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'', ...

(early

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...

stage)

Mocuio Formation The Mocuio Formation is a Late Cretaceous sedimentary rock formation found in southern Angola. It extends from the latest Campanian to the Early Maastrichtian. Many vertebrate fossils have been collected from the formation. Paleofauna See ...

Namibe Province Namibe Province is a province of Angola. Under Portuguese rule it was the Moçâmedes District. It has an area of 57,091 km2 and had a 2014 census population of 495,326. The port and city of Moçâmedes is the capital of the province with a ...

, southern

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

. It contains a single species, ''Cardiocorax mukulu''. Its length is estimated at .

Discovery

''Cardiocorax'' is known from the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

MGUAN PA103 which consists of a complete pectoral and pelvic girdle, five neck and one back vertebrae, a partial forelimb including the humerus,

radius bone The radius or radial bone is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna. The ulna is usually slightly longer tha ...

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

and isolated phalanges, and several dorsal ribs. A second specimen was also referred to the species, MGAUN PA270, a more complete articulated pelvic girdle and a single hind limb. Both specimens are housed at the Museu de Geologia da Universidade Agostinho Neto in

Luanda Luanda () is the Capital (political), capital and largest city in Angola. It is Angola's primary port, and its major Angola#Economy, industrial, Angola#Culture, cultural and Angola#Demographics, urban centre. Located on Angola's northern Atl ...

. The specimens were discovered at Bench 19 locality, about 7 meters from each other, in

Bentiaba The Bentiaba (or ''Rio de São Nicolau'' or Saint Nicolas River) is a river in southern Angola. Its mouth is at the Atlantic Ocean near the commune of Bentiaba in Namibe Province. The riverbank has produced a number of Cretaceous fossils includin ...

of the

. They were collected from the

of the Sāo Nicolau Group of Namibe Basin, dating to the early

stage of the

, 71.40–71.64

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago) ...

. In 2017

Octávio Mateus Octávio Mateus (born 1975) is a Portuguese dinosaur paleontologist and biologist Professor of Paleontology at the Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa. He graduated in Universidade de Évora and received his PhD at U ...

found a complete skull and partial postcrania also attributed to ''Cardiocorax''.

Etymology

''Cardiocorax'' was first named by Ricardo Araújo, Michael J. Polcyn, Anne S. Schulp,

, Louis L. Jacobs, A. Olímpio Gonçalves and M.-L. Morais in 2015 and the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

is ''Cardiocorax mukulu''. The generic name is derived from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

ised

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''Kardia'', meaning "heart", plus ''corax'', meaning "raven/crow" which is also the source of the name "

coracoid A coracoid (from Greek κόραξ, ''koraks'', raven) is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is prese ...

", in reference to the heart-shaped

fenestra A fenestra (fenestration; plural fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical st ...

between the coracoids which is unique to this genus. The specific name comes from the word ''mukulu'' in Angolan Bantu dialects, which means "ancestor".

Phylogeny

''Cardiocorax'' is a relatively distinctive

, possessing four unique traits, i.e.

autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...

. Notably, it shows a reduced dorsal blade of the

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eith ...

, a feature unique among elasmosaurids, but convergent with the related cryptoclidid plesiosaurs. This trait indicates a longitudinal protraction-retraction limb cycle rowing style with simple pitch rotation at the glenohumeral articulation - a style unique to ''Cardiocorax''. Araújo ''et al.'' (2015) tested the phylogenetic position of the genus using a modified version of Ketchum & Benson (2010) data-set, as well as a second data-set from Vincent ''et al.'' (2011) which was found to be consistent with the former. The

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

below follows their results.

References

{{Taxonbar, from=Q21127231 Elasmosaurids Maastrichtian life Late Cretaceous plesiosaurs Plesiosaurs of Africa Fossils of Angola Fossil taxa described in 2015 Taxa named by Octávio Mateus Sauropterygian genera