Upon its description in 1999, " Ambondro " was interpreted as a primitive relative of Tribosphenida ( marsupials, placentals, and their extinct tribosphenic-toothed relatives ).
22.
Some Jurassic mammals, such as " Shuotherium " and " Pseudotribos ", have " reversed tribosphenic " molars, in which the talonid is towards the front.
23.
Previous theories had suggested that these specialized tribosphenic molars _ which can simultaneously shear food and crush it in mortar-and-pestle fashion _ had evolved only once, in the Northern Hemisphere.
24.
With their versatile functions for chewing different kinds of food, the tribosphenic and pseudo-tribosphenic teeth are key evolutionary innovations that enabled some of the earliest mammals to diversify in the Mesozoic times.
25.
With their versatile functions for chewing different kinds of food, the tribosphenic and pseudo-tribosphenic teeth are key evolutionary innovations that enabled some of the earliest mammals to diversify in the Mesozoic times.
26.
Consequently, Flynn and colleagues argued against the prevailing view that tribosphenic mammals originated on the northern continents ( Laurasia ), and instead proposed that their origin lies in the south ( Gondwana ).
27.
The molar teeth were initially thought to be tribosphenic, which would have supported a variation of Gregory's theory, but later research has suggested, while they have three cusps, they evolved under a separate process.
28.
According to Luo " et al . ", tribosphenic molars were evolved by the Australosphenida independently of the true Tribosphenida, or Boreosphenida ( that is, the therians and their relatives ) in the northern continents.
29.
Modern mammals are all descendants from ancient mammals-- living with the dinosaurs in the Mesozoic-- with tribosphenic teeth ( " sphen " is Greek for shearing and cutting; " tribo " is Greek for grinding and pounding.
30.
The oldest undisputed fossils of " Dryolestidae " were found in the tribosphenic mammals, and they form a sister group of the latter and " Peramus " together with " Amphitherium ", Paurodontidae, and Henkelotheriidae.