Megatheriidae

Megatheriidae
Temporal range: Late Oligocene (Deseadan)-Early Holocene (Lujanian)
~29–0.008 Ma
Eremotherium skeleton, NMNH, Washington, DC.
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Pilosa
Clade: Megatheria
Family: Megatheriidae
J. E. Gray 1821
Type genus
Megatherium americanum
Subgroups
Closeup of hand, showing claws
Closeup of skull

Megatheriidae is a family of extinct ground sloths that lived from approximately 23 mya—11,000 years ago.

Megatheriids appeared during the Late Oligocene (Deseadan in the SALMA classification), some 29 million years ago, in South America. The group includes the heavily built Megatherium (given its name 'great beast' by Georges Cuvier) and Eremotherium. An early genus that was originally considered a megatheriid, the more slightly built Hapalops, reached a length of about 1.2 metres (3.9 ft). The nothrotheres have recently been placed in their own family, Nothrotheriidae.

The skeletal structure of these ground sloths indicates that the animals were massive. Their thick bones and even thicker joints (especially those on the hind legs) gave their appendages tremendous power that, combined with their size and fearsome claws, provided a formidable defense against predators.

The earliest megatheriid in North America was Sibotherium which arrived 5.3 million years ago, after crossing the recently formed Panamanian land bridge. At more than five tons in weight, 6 metres (20 ft) in length, and able to reach as high as 5.2 metres (17 ft), Eremotherium was taller than an African bush elephant bull. Unlike relatives, this species retained a plesiomorphic extra claw. While other species of Eremotherium had four fingers with only two or three claws, E. eomigrans had five fingers, four of them with claws up to nearly 30 centimetres (1 ft) long.

Phylogeny

The following sloth family phylogenetic tree is based on collagen and mitochondrial DNA sequence data (see Fig. 4 of Presslee et al., 2019).

  Folivora  

Megalocnidae† (Caribbean sloths)

  Nothrotheriidae  

Nothrotheriops shastensis†    

  Megatheriidae  

Megatherium americanum

  Megalonychidae  

Megalonyx jeffersoni

Bradypodidae
  (three-fingered sloths)  

B. torquatus

B. pygmaeus

B. tridactylus

B. variegatus

Megatherioidea

Scelidotheriidae

Choloepodidae (two-fingered sloths)

Mylodontidae

Mylodontoidea

The following phylogeny is based on Varela et al. 2019.

Folivora

Pseudoglyptodon

Bradypodidae 

Bradypus

Eufolivora 
Mylodontidae 

Nematherium

Scelidotheriinae 

Analcitherium

Neonematherium

Sibyllotherium

Proscelidodon

Catonyx

Scelidotherium

Valgipes

Pseudoprepotherium

Orophodontinae

Brievabradys

Octodontotherium

Paroctodontotherium

Octomylodon

Urumacotherium

Baraguatherium

Octodontobradys

Mylodontinae 

Mylodon

Thinobadistes

Lestodon

Lestobradys

Bolivartherium

Simomylodon

Pleurolestodon

Glossotherium

Paramylodon

Megatherioidea 

Schismotherium

Pelecyodon

Megalonychidae 

Hapalops

Hyperleptus

Eucholoeops

Pseudortotherium

Megalonychotherium

Megalonychinae 

Pliometanastes

Megalonyx

Australonyx

Megistonyx

Ahytherium

Pliomorphus

Megalocninae 

Megalocnus

Parocnus

Choloepodinae 

Acratocnus

Neocnus

Choloepus

Megatheria 

Analcimorphus

Nothrotheriidae 
Thalassocninae 

Thalassocnus

Nothrotheriinae 

Lakukullus

Mionothropus

Nothrotherium

Nothrotheriops

Pronothrotherium

Aymaratherium

Xyophorus

Megatheriidae 
Planopsinae 

Prepoplanops

Planops

Prepotherium

Megatheriinae 

Diabolotherium

Megathericulus

Anisodontherium

Pyramiodontherium

Proeremotherium

Eremotherium

Megatherium


This page was last updated at 2023-12-15 01:34 UTC. Update now. View original page.

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