Rebbachisauridae
Encyclopedia
Rebbachisauridae is a family
of sauropod dinosaur
s known from fragmentary fossil
remains from the Cretaceous
of South America
, Africa
, and Europe
.
in 1990 included the first known genus, the giant North African sauropod Rebbachisaurus
in the family Diplodocidae, subfamily Dicraeosaurinae
, on the basis of skeletal details. With the discovery in subsequent years of a number of additional forms, it was realised that the rebbachisaurs constitute a distinct group of dinosaurs, and in 1997 the Argentine paleontologist José Bonaparte
named the family Rebbachisauridae. Whitlock, 2011 defined two new subfamilies Nigersaurinae and Limaysaurinae within Rebbachisauridae. Cladogram
of the Rebbachisauridae after Whitlock, 2011.
Cladogram based on Carballido et al. (2010) and Sereno et al. (2007):
Although all authorities agree that the rebbachisaurids are members of the superfamily Diplodocoidea
, they lack the bifid (divided) cervical
neural spines that characterise the diplodocids and dicraeosaurids
, and for this reason are considered more primitive than the latter two groups. It is not yet known whether they share the distinctive whip-tail of the latter two taxa.
Rebbachisaurids are distinguished from other sauropods by their distinctive teeth, which have low angle, internal wear facets and asymmetrical enamel
.
Unique among sauropods, at least some rebbachisaurids (such as Nigersaurus
) are characterised by the presence of tooth batteries, similar to those of hadrosaur and ceratopsia
n dinosaurs. Such a feeding adaptation has thus developed independently three times among the dinosaurs.
So far, rebbachisaurids are known only from the middle and early part of the Late Cretaceous. Unless the nemegtosaurids
are in fact diplodocoids (rather than titanosaur
s), then the rebbachisaurids represent the last known representatives of this clade, and lived alongside the titanosaurs until fairly late in the Cretaceous. So far, no rebbachisaurids are known from the very end of the Cretaceous period.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of sauropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s known from fragmentary fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
remains from the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
of 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...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
.
Taxonomy
Sauropod specialist Jack McIntoshJack McIntosh
John McIntosh was a Progressive Conservative party member of the Canadian House of Commons. He was born in Wick, Caithness, Scotland and became a merchant by career....
in 1990 included the first known genus, the giant North African sauropod Rebbachisaurus
Rebbachisaurus
Rebbachisaurus is a genus of sauropod dinosaur of the superfamily Diplodocoidea, up to 20 meters long, that lived during the Early-Late Cretaceous period in Africa about 99 million years ago. This massive four-legged plant-eating animal had a small head, a long, graceful neck and a whiplike...
in the family Diplodocidae, subfamily Dicraeosaurinae
Dicraeosauridae
Dicraeosauridae is a family of sauropod dinosaurs known from the Late Jurassic and Early Cretaceous of Africa and South America. Currently only three genera are recognised; the Jurassic South American genus Brachytrachelopan, the Jurassic African Dicraeosaurus and the South American Early...
, on the basis of skeletal details. With the discovery in subsequent years of a number of additional forms, it was realised that the rebbachisaurs constitute a distinct group of dinosaurs, and in 1997 the Argentine paleontologist José Bonaparte
José Bonaparte
José Fernando Bonaparte, Ph.D. , is an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists like Rodolfo Coria...
named the family Rebbachisauridae. Whitlock, 2011 defined two new subfamilies Nigersaurinae and Limaysaurinae within Rebbachisauridae. Cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
of the Rebbachisauridae after Whitlock, 2011.
Cladogram based on Carballido et al. (2010) and Sereno et al. (2007):
Evolutionary relationships and characteristics
Diplodocoidea
Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias...
, they lack the bifid (divided) cervical
Cervical vertebrae
In vertebrates, cervical vertebrae are those vertebrae immediately inferior to the skull.Thoracic vertebrae in all mammalian species are defined as those vertebrae that also carry a pair of ribs, and lie caudal to the cervical vertebrae. Further caudally follow the lumbar vertebrae, which also...
neural spines that characterise the diplodocids and dicraeosaurids
Dicraeosauridae
Dicraeosauridae is a family of sauropod dinosaurs known from the Late Jurassic and Early Cretaceous of Africa and South America. Currently only three genera are recognised; the Jurassic South American genus Brachytrachelopan, the Jurassic African Dicraeosaurus and the South American Early...
, and for this reason are considered more primitive than the latter two groups. It is not yet known whether they share the distinctive whip-tail of the latter two taxa.
Rebbachisaurids are distinguished from other sauropods by their distinctive teeth, which have low angle, internal wear facets and asymmetrical enamel
Tooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...
.
Unique among sauropods, at least some rebbachisaurids (such as Nigersaurus
Nigersaurus
Nigersaurus is a genus of diplodocoid sauropod dinosaur from the middle Cretaceous period, about 119 to 99 million years ago during the Aptian or Albian age. This dinosaur was described by Paul Sereno and colleagues in 1999...
) are characterised by the presence of tooth batteries, similar to those of hadrosaur and ceratopsia
Ceratopsia
Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7...
n dinosaurs. Such a feeding adaptation has thus developed independently three times among the dinosaurs.
So far, rebbachisaurids are known only from the middle and early part of the Late Cretaceous. Unless the nemegtosaurids
Nemegtosauridae
Nemegtosauridae is a family of probably titanosaurian sauropod dinosaurs based originally on two late Cretaceous Mongolian species known only from their diplodocid-like skulls: Nemegtosaurus and Quaesitosaurus. Authorities disagree as to the relationship of these two genera with other sauropods,...
are in fact diplodocoids (rather than titanosaur
Titanosaur
Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...
s), then the rebbachisaurids represent the last known representatives of this clade, and lived alongside the titanosaurs until fairly late in the Cretaceous. So far, no rebbachisaurids are known from the very end of the Cretaceous period.