Question

Which clade does not include humans?

(A) synapsids

(B) lobe-fins

(C) diapsids

(D) osteichthyans

Short answer

(A) The option"synapsids" is false.

(B) The option "lobe-fins" is false.

(C) The option "diapsids" is true.

(D) The option “osteichthyans” is false.

Step-by-step solution

Human beings

Human beings are mammals that can socialize; these organisms evolved over millions of years. Today's humans are tetrapods with bipedal locomotion and have a bony endoskeleton; all these traits evolved from ancestral traits. Humans are a part of many different clades due to these similarities.

Explanation of option '(A)'

The synapsid clade incorporates mammalian organisms (including humans) and some reptiles. This clade has a single hole within the skull's temporal bone (often denoted as temporal fenestrae) on either side.

Thus, humans do belong to the synapsid clade.

Therefore, the given option is false.

Explanation of option '(B)'

The lobe-fin is a clade of bony fishes which are rarely found today, but the lobed structure of their fins resembles the lobed structure of human limbs. This and other evolutionary data suggest that humans descended from the lobe-fins clade.

Thus, the clade of lobe-fins does include human beings.

Therefore, the given option is false.

Explanation of option '(C)'

The term diapsid refers to the group of organisms that comprises dual temporal fenestrae (holes in the temporal bone) on the skull's either side. This trait is found mainly in the class Reptilia and class Aves.

Thus, the clade diapsids do not include humans or any other mammals.

Therefore, the given option is true.

Explanation of option '(D)'

The clade osteichthyans comprise animals that have bony tissues in their skeleton. This includes the bony fishes, both ray-finned and lobe-finned, and all the organisms that descended from these bony fishes. Humans descended from lobe-finned bony fishes are also a part of this clade.

Thus, the osteichthyans clade does include human beings.

Therefore, the given option is false.