Fossils of thrinaxodon, a species that lived during the triassic period, have been found in both south africa and antarctica. thrinaxodon had a reptile-like skeleton and laid eggs, but small depressions on the front of its skull suggest it had whiskers and, therefore, fur. thrinaxodon may have been warm-blooded. the fossils of thrinaxodon are consistent with the hypothesis that ) fossils found in a given area look like the modern species in that same area
b) the environment where it lived was very warm
c) mammals evolved from a reptilian ancestor
d) antarctica and south africa separated after thrinaxodon went extinct

C) mammals evolved from a reptilian ancestor

Explanation:

Mammals, amphibians, and reptiles are tetrapods. Reptiles and mammals are shown to be originated from a common ancestor, the early tetrapods which in turn diversified into two lineages. One of the lineages evolved into synapsids and the other gave rise to reptiles and birds. Synapsids diversified into two lineages one of which later formed mammals.

According to the given information, fossil records of Thrinaxodon have a reptile-like skeleton and were oviparous like reptiles. However, the presence of furs and the possibility of being warm-blooded make it like a mammal.

Reptiles are cold-blooded egg-laying tetrapods while mammals are warm-blooded viviparous tetrapods. The presence of some of the features from both the groups in Thrinaxodon provides proof that mammals evolved from a reptilian ancestor.

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.