| Magdalenabradys | |
|---|---|
 | |
| Mandible ofMagdalenabradys confusum | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Pilosa |
| Family: | †Mylodontidae |
| Tribe: | †Lestodontini |
| Genus: | †Magdalenabradys Rincón and McDonald,2020 |
| Type species | |
| †Magdalenabradys confusum Hirschfeld (1985) | |
| Other species | |
| |
| Synonyms | |
Pseudoprepotherium confusum Hirschfeld (1985) | |
Magdalenabradys is an extinct genus ofmylodontid ground sloths that lived during the Middle Miocene and Early Pliocene of what is nowColombia andVenezuela. Fossils have been found in theVillavieja Formation of theHonda Group in Colombia, and theCodore andUrumaco Formations of Venezuela.
The first remains ofMagdalenabradys were found in the Villavieja Formation of the Honda Group in the strata of theTatacoa Desert of theHuila Department. The holotype ofM. confusum was found about 9 km east of Villavieja and 2.5 km northeast of Hacienda Argentina, Huila. The holotype consisted of a crushed and distorted skull. The femur is based on eight specimens from six localities, including one femur from a partial skeleton that included a skull and mandible (specimens UCMP 3800, 37999). The cranium and partial mandible of both species were originally assigned toBolivartherium urumaquensis.
The generic name,Magdalenabradys is derived from theMagdalena River, in which the type specimen was found andconfusum meaning "confused" in reference to the fact that it has originally been confused withPseudoprepotherium. A second species,M. kolossiaia, was named in 2020. The specific epithet means "colossal".[1]
Magdalenabradys confusum was originally assigned to the genusPseudoprepotherium bySue Ellen Hirschfeld in 1985.[2] However, it was subsequently found to be a distinct genus 35 years later in 2020.Magdalenabradys is considered to be a derived mylodontid, closely related toLestodon,Pseudoprepotherium, andThinobadistes.[1]
Below is a phylogenetic tree of the Mylodontidae, based on the work of Rincón and McDonald 2020, showing the position ofMagdalenabradys.
The most extensive fossil material to date belongs to the Urumaco sequence, a complex depositional unit that is predominantly exposed in the approximately 36,000 km2 largeFalcón Basin in the Venezuelan state ofFalcón. It is composed of the lithostratigraphic units of theUrumaco andCodore Formations, with remains ofMagdalenabradys being limited to the former formation. The Urumaco sequence covers the Middle Miocene to theEarly Pliocene. The main components are different layers of sand, clay and/silt and limestone in which individual coal seams are embedded, at least in the Urumaco Formation. The rock strata were formed in what was originally a coastal area under the influence of a river delta.[3] From the entire Urumaco sequence, a large number of sites are documented, the exploration of which began as early as the 1950s. They are distributed over a good 60 different stratigraphic levels. The find material consists mainly of fish, especially sharks and rays. In addition, there are also reptiles such as turtles, crocodilians and isolated snakes, as well as mammals appearing with rodents, South American ungulates,manatees, and minor jointed animals among others. The secondary articulated animals show a high diversity, which almost reaches that of the contemporary fauna of southern South America in the Pampas region or inMesopotamia. Armadillos such as thePampatheriidae andGlyptodontinae as well as sloths have been found.[4][5][6] Mainly in the late 20th and early 21st century, numerous new forms were described, such asUrumacocnus andPattersonocnus from the familyMegalonychidae,Urumaquia andProeremotherium as representatives of the large familyMegatheriidae andBolivartherium,Pseudoprepotherium,Eionaletherium andUrumacotherium from the family Mylodontidae and their immediate relatives. As a special circumstance of taphonomy, the frequent tradition of limb elements in sloths is to be evaluated, however, fromMagdalenabradys, skull remains are also documented.[7][8]
The Honda Group in Colombia is known for its diverse abundance of fauna, such as xenarthrans, ungulates, primates, rodents, metatherians, crocodilians, turtles, snakes, birds, and fish. There are 2 subunits of the Honda Group; the Villavieja Formation and theLa Victoria Formation.Magdalenabradys fossils are only known from the former formation of the Honda Group.
Mammals from the Honda Group included the fellow mylodontid slothsBrievabradys andGlossotheriopsis,[9] as well as thescelidotheriidNeonematherium, the basal megatherioidHapalops and the nothrotheriidHuilabradys, cingulates such as thedasypodidsAnadasypus andNanoastegotherium, thepachyarmathereNeoglyptatelus, thepampathereScirrotherium, and the glyptodontBoreostemma. In addition, the anteaterNeotamandua was also present. Ungulates from the Honda Group included theastrapotheresGranastrapotherium,Hilarcotherium, andXenastrapotherium, the litopternsMegadolodus,[10]Mesolicaphrium,Neodolodus,Theosodon, andVillarroelia, and thenotoungulatesHuilatherium,Pericotoxodon, andMiocochilius.[11][12] Metatherians from the Honda group included the sparassodontsAnachlysictis,Dukecynus,Hondadelphys, andLycopsis, themicrobiotheriansMicoureusPachybiotherium, thedidelphidThylamys, thepaucituberculatesHondathentes andPitheculites. Rodents of the Honda Group included various genera of caviomorphs, such asAcarechimys,Eodolichotis,Microscleromys,Microsteiromys,Neoreomys,OlenopsisProdolichotis,Rhodanodolichotis,Ricardomys,Scleromys, andSteiromys. Birds of the Honda Group included the speciesAramus paludigrus,Galbula hylochoreutes, andHoazinoides magdalenae. Reptiles of the Honda Group included crocodylomorphs, snakes, and turtles, such as thesebecidLangstonia, thealligatoridsBalanerodus,Eocaiman,Mourasuchus andPurussaurus the gavialidGryposuchus, and the crocodileCharactosuchus, the turtlesChelus colombiana,Podocnemis medemi, andGeochelone hesterna, and the snakesColombophis andEunectes stirtoni.[13]
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