''Bonapartesaurus'' (meaning "Bonaparte's lizard", named after

José Bonaparte José Fernando Bonaparte (14 June 1928 – 18 February 2020) was an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists . One of the best-known Argentine paleo ...

) is an extinct

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 ...

of herbivorous

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

belonging to

Hadrosauridae Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which includ ...

, which lived in the area of modern

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

during the

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 ...

and

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 from ...

stages of 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 ...

Discovery and naming

The remains were excavated by the Argentine paleontologist Jaime Powell and collaborators in 1984 and described by him in 1987, where he identified the dinosaur remains as a possible "indeterminate lambeosaurine", comparing it mainly with the genera ''

Hypacrosaurus ''Hypacrosaurus'' (meaning "near the highest lizard" reek υπο-, ''hypo-'' = less + ακρος, ''akros'', high because it was almost but not quite as large as ''Tyrannosaurus'') was a genus of duckbill dinosaur similar in appearance to ''Co ...

'' and ''

Barsboldia ''Barsboldia'' (meaning "of Barsbold", a well-known Mongolian paleontologist) is a genus of large hadrosaurid dinosaur from the early Maastrichtian Nemegt Formation of Ömnogöv', Mongolia. It is known from a partial vertebral column, parti ...

'' due to great size of the neural spines. In 2010, Rubén D. Juárez Valieri and his team erected a new genus and hadrosaurid species called '' Willinakaqe salitralensis'' from different materials found in 2 different locations (Salitral Moreno and Islas Malvinas) of the

Allen Formation The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous (middle Campanian to early Maastrichtian.Salgado et al., 2007 Dinosaur remains are among the fossils that have been recovered from the formati ...

, which are mostly housed in the collection of the Carlos Ameghino Provincial Museum, where the specimen was examined by Powell, and was made 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 nor a syntype). Of ...

of this new genus, in addition to the holotype of '' Lapampasaurus'' as material attributed to ''W. salitralensis'' from the second locality and housed in the Provincial Museum of Natural History, in the province of La Pampa. Later, the Spanish paleontologist Penélope Cruz-Caballero and the Argentine Rodolfo Coria reviewed the material attributed to the genus ''Willinakaqe'' in 2016, where they concluded that fossils may represent more than one taxon of hadrosaurid and that the characteristics used in the diagnosis would not be valid. Also, the specimen is not preserved in good condition in addition to being incomplete, and therefore non-diagnostic, degrading it to the status of "indeterminate Hadrosauridae" and making ''Willinakaqe salitrensis'' a '' Nomen vanum''. In 2017 Cruzado-Caballero and Powell reassign the paratype of ''W. salitralensis'' to its own genus and species, ''Bonapartesaurus rionegrensis'', converting the former into a

chimera Chimera, Chimaera, or Chimaira (Greek for " she-goat") originally referred to: * Chimera (mythology), a fire-breathing monster of Ancient Lycia said to combine parts from multiple animals * Mount Chimaera, a fire-spewing region of Lycia or Cilicia ...

of different hadrosaurids, and hence, an invalid name.

Description

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 ...

specimen MPCA-Pv SM2/1-71, consists of a partial skeleton including 4 dorsal

vertebra 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 ...

e, a complete

sacrum The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, 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 ...

, 8 anterior caudal vertebrae, 9 medial caudal vertebrae, 2 blocks with 5 medial caudal vertebrae each, 18

haemal arch A haemal arch also known as a chevron, is a bony arch on the ventral side of a tail vertebra of a vertebrate. The canal formed by the space between the arch and the vertebral body is the haemal canal. A spinous ventral process emerging from the hae ...

es, 3 dorsal

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

s, a distal fragment of the right

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 ...

, a distal fragment of the left

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 ...

, a left

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 ...

, a right ilium, a nearly complete left pubis, distal fragments of both

ischia Ischia ( , , ) is a volcanic island in the Tyrrhenian Sea. It lies at the northern end of the Gulf of Naples, about from Naples. It is the largest of the Phlegrean Islands. Roughly trapezoidal in shape, it measures approximately east to west ...

, both

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 ...

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

s, and

fibula The fibula 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. Its upper extremity is ...

e, a left

astragalus ''Astragalus'' is a large genus of over 3,000 species of herbs and small shrubs, belonging to the legume family Fabaceae and the subfamily Faboideae. It is the largest genus of plants in terms of described species. The genus is native to tempe ...

, a right

calcaneus In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel) or heel bone is a bone of the tarsus of the foot which constitutes the heel. In some other animals, it is the point of the hock. S ...

, an almost complete articulated left foot and two blocks with

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

s. All the material present was extracted from the Salitral Moreno site of the

Río Negro province Río Negro (, ''Black River'') is a province of Argentina, located in northern Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean. Its capit ...

in southern Argentina, from the lower member of the

, which dates to the

(

). ''Bonapartesaurus'' is characterized by the following combination of unique characters: the proportion between the height of the neural, sacral and centrum spines is greater than 3.5; the

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 of the anterior part of the caudal vertebrae are extremely long (between three and a half and four times the height of the centrum) and evenly the distal expansion; a pre-acetabular process slightly flexed ventrally, with the angle greater than 150°; the proportion between the maximum dorsoventral depth of the posterior end of the dorsoventral preacetabular process and the distance from the pubic peduncle to the dorsal margin of the iliac bone is inferior to 0,50; The ratio between height and anteroposterior dorsoventral length of the iliac lamina is 0.8 or higher; an asymmetric lateral profile of the supraacetabular process; the posterior portion of the mediolateral postacetabular process markedly thicker as a result of the dorsomedial torsion of the postacetabular process; an expanded cnemial crest limited anteriorly to the proximal end of the tibia; and the articular surface of the astragalus for the internal

malleolus A malleolus is the bony prominence on each side of the human ankle. Each leg is supported by two bones, the tibia on the inner side (medial) of the leg and the fibula on the outer side (lateral) of the leg. The medial malleolus is the promine ...

of the tibia is moderately expanded medially, articulating with only a part of the ventral surface of the tibial internal malleolus.

Phylogeny

The only

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 ...

analysis of ''Bonapartesaurus'' follows Paul Sereno's definition for Hadrosauridae from 1998, in addition to using the traditional classification of Hadrosaurinae (prior to the consensus of Prieto-Marquez in 2010), which includes all non-crested hadrosaurids along with the fragmentary genus ''

Hadrosaurus ''Hadrosaurus'' (; ) is a genus of hadrosaurid ornithopod dinosaurs that lived in North America during the Late Cretaceous Period in what is now the Woodbury Formation about 80 million to 78 million years ago. The holotype specimen was found in f ...

'' within the same subfamily. It is also placed within the Saurolophini tribe, being more derived than ''

Prosaurolophus ''Prosaurolophus'' (; meaning "before ''Saurolophus''", in comparison to the later dinosaur with a similar head crest) is a genus of hadrosaurid (or duck-billed) dinosaur from the Late Cretaceous of North America. It is known from the remains of ...

'', but more basal than ''

Saurolophus ''Saurolophus'' (; meaning "lizard crest") is a genus of large hadrosaurid dinosaur from the Late Cretaceous period of Asia and North America, that lived in what is now the Horseshoe Canyon and Nemegt formations about 70 million to 68 million ...

'' spp., in contrast to the tentative classification of '' Willinakaqe'' within the

Kritosaurini Kritosaurini is a tribe of saurolophine hadrosaurid dinosaurs from the Late Cretaceous. Discovery and naming The first member of the group discovered and named was ''Kritosaurus''; it was named by paleontologist Barnum Brown in 1910. Four year ...

tribe. The following

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 ...

is based on the phylogenetic analysis of Cruzado-Caballero & Powell in 2017. (Relations with Lambeosaurinae as well as with Hadrosauroidea are not shown here).

References

{{Taxonbar, from=Q29941319 Saurolophines Campanian life Maastrichtian life Late Cretaceous dinosaurs of South America Cretaceous Argentina Fossils of Argentina Allen Formation Fossil taxa described in 2017 Ornithischian genera

Discovery and naming

Description

Phylogeny

See also

References