Cladotheria

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Cladotheria
Temporal range: Middle JurassicHolocene, 165–0 mya
Kangaroo and joey03.jpg
Kangaroo with her joey
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Clade: Trechnotheria
Clade: Cladotheria
McKenna, 1975
Subgroups

Cladotheria is a taxonomic group. It includes two of the three living groups of mammals. These are the placental mamnals and the marsupials. The monotremes are not in this group, but all other living mammals are in the group.[1]

The Cladotheria also includes some groups which have become extinct.[2]

Common traits[change | change source]

Members of the group have a number of common traits:

  • They give birth to live young (as opposed to the egg-laying monotremes)
  • They have two separate openings, one for the anus, and the other one for the urethra (the monotremes have just one opening)
  • The shoulder area only has two bones, the scapula (shoulder blade), and the clavicula
  • The mammary glands are connected to teats
  • Their skull has a common layout
  • On their face they have hairs called whiskers which are sensitive to touch.
  • Their molars have a common pattern.

References[change | change source]

  1. Rowe, Timothy (1988). "Definition, diagnosis, and origin of Mammalia". Journal of Vertebrate Paleontology. 8 (3): 241–264. doi:10.1080/02724634.1988.10011708. ISSN 0272-4634.
  2. Zofia Kielan-Jaworowska, Richard L. Cifelli, and Zhe-Xi Luo 2004. Mammals from the Age of Dinosaurs: origins, evolution, and structure. New York: Columbia University Press.