''Malawisaurus'' (meaning "

Malawi Malawi (; or aláwi Tumbuka: ''Malaŵi''), officially the Republic of Malawi, is a landlocked country in Southeastern Africa that was formerly known as Nyasaland. It is bordered by Zambia to the west, Tanzania to the north and northe ...

lizard") 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 n ...

of titanosaurian

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their ...

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 ...

. It is known from the Dinosaur Beds of northern Malawi, which probably date to the

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ag ...

stage of the

Early Cretaceous The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pr ...

. The type species is ''M. dixeyi'' and the specific name honours

Frederick Augustus Dixey Frederick Augustus Dixey, FRS (9 December 1855 – 16 January 1935) was president of the Royal Entomological Society of London, and was a distinguished British entomologist. Frederick Dixey was educated at Highgate School from 1867 to 1874, and ...

Discovery and naming

''Malawisaurus dixeyi'' was originally described in 1928 by Sidney H. Haughton as a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

of '' Gigantosaurus'' (an invalid name for the

diplodocid Diplodocids, or members of the family Diplodocidae ("double beams"), are a group of sauropod dinosaurs. The family includes some of the longest creatures ever to walk the Earth, including ''Diplodocus'' and ''Supersaurus'', some of which may have ...

currently known as '' Tornieria''). Haughton considered it closely related to the species ''G. robustus'' (later 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( ...

of '' Janenschia''). The holotype was discovered in the " Dinosaur Beds" of Malawi (then known as the Nyasaland Protectorate), which are usually considered to be of

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma ( million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is pre ...

age based on K–Ar dating, though they have also been suggested to be Late Cretaceous in age based on the vertebrate assemblage, and possibly also the

Lupata Group The Lupata Group is an Aptian geologic group in the Tete Province of Mozambique and the Northern Region of Malawi. The group contains the Dinosaur Beds, a fossiliferous unit in Malawi that has provided dinosaur remains.Weishampel, et al. (20 ...

. In 1993 it was placed in the newly named genus ''Malawisaurus'' by

Louis L. Jacobs Louis Leo Jacobs (born August 27, 1948) is an American vertebrate paleontologist who discovered ''Malawisaurus'' while on an expedition in Malawi. Much of his research concerns the interrelationships of Biotic component, biotic and abiotic events ...

and colleagues, based on newly collected material from the locality. 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 seve ...

is SAM 7405, a partial skeleton and its type locality is Mwakasyunguti. ''Malawisaurus'' is not known outside of

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

- however, an isolated

tooth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...

resembles those associated with ''Malawisaurus'' and was found in 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'', ...

( Cenomanian)-aged Alcântara Formation of

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

according to a report in 2007. It is currently listed as "Titanosauria indet., possibly ''Malawisaurus'' .sp".

Description

Relatively small by sauropod standards, ''Malawisaurus'' reached lengths of about , and weighed about . In 2020 it was given a smaller estimation of 11 meters (36 ft) and 2.8 tonnes (3.1 short tons). Like some other titanosaurs, ossicles have been found which are believed to represent dermal scutes that covered the skin. The vertebrae from the middle part of its tail had elongated centra. ''Malawisaurus'' had vertebral lateral fossae that resembled shallow depressions. Fossae that similarly resemble shallow depressions are known from '' Saltasaurus'', '' Alamosaurus'', '' Aeolosaurus'', and '' Gondwanatitan''.

Classification

By definition, ''Malawisaurus'' has to be the most basal lithostrotian. The cladogram below follows Franca ''et al.'' (2016).

References

Footnotes

* S. H. Haughton. 1928. On some reptilian remains from the Dinosaur Beds of Nyasaland. Transactions of the Royal Society of South Africa 16:67-75 * Paul, Gregory S. (2010) ''The Princeton Field Guide to Dinosaurs''. * Tidwell, V., Carpenter, K. & Meyer, S. 2001. New Titanosauriform (Sauropoda) from the Poison Strip Member of the Cedar Mountain Formation (Lower Cretaceous), Utah. In: Mesozoic Vertebrate Life. D. H. Tanke & K. Carpenter (eds.). Indiana University Press, Eds. D.H. Tanke & K. Carpenter. Indiana University Press. 139-165.

External links

page on ''Malawisaurus'' from DinoDictionary.

New material of an Early Cretaceous titanosaurid dinosaur of Malawi

* ttps://web.archive.org/web/20110715174436/http://www.rescast.com/specimens/show_select_specimen.php?SpecimenID=48 Research Casting International - ''Malawisaurus dixeyi'' {{Taxonbar, from=Q133655 Lithostrotians Aptian life Early Cretaceous dinosaurs of Africa Cretaceous Malawi Fossils of Malawi Fossil taxa described in 1993 Taxa named by Louis L. Jacobs