''Albertonectes'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 ...

plesiosaur The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared ...

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'', the ...

(middle upper

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...

stage)

Bearpaw Formation The Bearpaw Formation, also called the Bearpaw Shale, is a geologic formation of Late Cretaceous (Campanian) age. It outcrops in the U.S. state of Montana, as well as the Canadian provinces of Alberta and Saskatchewan, and was named for the Bear P ...

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

. It contains a single species, ''Albertonectes vanderveldei''. ''Albertonectes'' is the longest elasmosaur, and more generally

, known to date both in neck and total body length.

Discovery

''Albertonectes'' is known solely 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 several ...

TMP 2007.011.0001, a complete well preserved

postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...

skeleton A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...

housed at the

Royal Tyrrell Museum of Palaeontology The Royal Tyrrell Museum of Palaeontology (RTMP, and often referred to as the Royal Tyrrell Museum) is a palaeontology museum and research facility in Drumheller, Alberta, Canada. The museum was named in honour of Joseph Burr Tyrrell, and is sit ...

in Drumheller, Alberta. Elements include all 132 vertebrae from the atlas-axis complex to fused tip of the

tail vertebrae The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordate ...

, complete pectoral and incomplete pelvic girdles, almost complete forelimbs and hindlimbs, disarticulated ribs, a gastralium, and at least 97 associated

gastrolith A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In othe ...

s. TMP 2007.011.0001 was discovered during mining for gem-quality

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

shell called

Ammolite Ammolite is an opal-like organic gemstone found primarily along the eastern slopes of the Rocky Mountains of North America. It is made of the fossilized shells of ammonites, which in turn are composed primarily of aragonite, the same mineral co ...

by Korite International Ltd. about 150 meters south of the St. Mary River near

Lethbridge Lethbridge ( ) is a city in the province of Alberta, Canada. With a population of 101,482 in its 2019 Alberta municipal censuses, 2019 municipal census, Lethbridge became the fourth Alberta city to surpass 100,000 people. The nearby Canadian ...

in southern Alberta. The specimen was excavated in a nearly completely articulated state from dark gray

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too sm ...

in a concretionary horizon about 15 m above the base of the Bearpaw Formation and about 2 m below an ash bed known by mine workers as the "10 inch bentonite". Collected from the lower part of Muddy Unit 1 of the St. Mary River Section, just below the lowest known local occurrence of '' Baculites compressus'' in the formation, the specimen is not younger than about 73.5 million years old and approximately of that age, thus dating to the middle of the upper

stage of the

. The discovery of ''Albertonectes'' marks a new record in both neck and total body length among known elasmosaurs, at in postcranial body length ( with skull) and a 7-meter (23-foot) neck.

Etymology

''Albertonectes'' was first described and named by Tai Kubo, Mark T. Mitchell and Donald M. Henderson in

2012 File:2012 Events Collage V3.png, From left, clockwise: The passenger cruise ship Costa Concordia lies capsized after the Costa Concordia disaster; Damage to Casino Pier in Seaside Heights, New Jersey as a result of Hurricane Sandy; People gather ...

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 specimen ...

is ''Albertonectes vanderveldei''. The generic name is derived from ''

'', in reference to the Canadian province where the holotype was found, and from

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 ...

''nectes'', meaning "swimmer", a common suffix for genus names of

plesiosauria The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeare ...

ns. The specific name honors the late Rene Vandervelde, the founder of Korite International, the gem-mining company that discovered the holotype.

Description

''Albertonectes'' has the longest neck of any elasmosaur ever discovered, which reached up to . The holotype, missing the skull, measures at from the atlas-axis complex to the tip of the tail, suggesting a total body length of with the skull. An long individual would have weighed . ''Albertonectes'' is also unique among other

s in having 76 neck vertebrae, a record number among elasmosaurids. ''Callawayasaurus'' with a similar count of 56 lacks the dumbbell-shaped articular faces that are present on the vertebrae of ''Vegasaurus''. Additional traits rarely seen in other elasmosaurids include: a tapered front-side projection on the pubis that extends to the side beyond the

acetabulum The acetabulum (), also called the cotyloid cavity, is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint. Structure There are three bones of the ''os coxae'' (hip bone) that c ...

, a longitudinal ridge on the side of most neck vertebrae up to cervical 69, a

clavicular The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the rig ...

arch that is wider than the adjacent front edge 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 eithe ...

, the lack of pectoral and pelvic bar, a tip of the tail that is made of seven fused tail vertebrae, and a slender

humerus The humerus (; ) 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 of a roun ...

with a width-to-length ratio of 0.56, among other traits. ''Albertonectes'' is known from a mature individual, as suggested by the fused

neural spine The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

s and most cervical ribs to their centra, and by the only partial connection between the

trochanter A trochanter is a tubercle of the femur near its joint with the hip bone. In humans and most mammals, the trochanters serve as important muscle attachment sites. Humans are known to have three trochanters, though the anatomic "normal" includes ...

and the capitulum (head) of the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

, seen in TMP 2007.011.0001. Other observation also support an adult age, e.g. rough and wrinkled vertebral surfaces as well as well-developed facets and articulations on its

wrist In human anatomy, the wrist is variously defined as (1) the Carpal bones, carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; "The wrist contains eight bones, roughly aligned in two rows, known ...

and

ankle The ankle, or the talocrural region, or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular join ...

bones.

Phylogeny

Kubo ''et al.'' (2012) tested the

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

position of ''Albertonectes'' using a highly modified version of Sato (2002)'s data-set, however its position wasn't stable and many

s formed rather large polytomies. This analysis was modified by O’Gorman ''et al.'' (2015), and 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 d ...

below follows their results, showing only the relationships within Elasmosauridae.

References

{{Taxonbar, from=Q149959 Fossil taxa described in 2012 Elasmosaurids Late Cretaceous plesiosaurs of North America Sauropterygian genera

Discovery

Etymology

Description

Phylogeny

See also

References