canicula (and other cat shark species) brain was the distinct brain vesicles including an enlarged telencephalon, making its brain structure more similar to that of the amniotes rather than the
anamniotes. A possible reason for this could be that when the cat shark hatches they are more developed as they have a longer developmental period compared with
anamniotes such as zebrafish or Xenopus and do not have a larval stage.
The vertebrates, for example, are subdivided into amniotes (reptiles, birds, and mammals) and
anamniotes (fishes and amphibians) based on whether they possess an amnion--a protective embryonic coveting.
Although amphibians are among the most sensitive
anamniotes to changes in the external medium, they were able to colonise a wide range of habitats in different environments (Duellman and Trueb, 1994).