According to the links below in carbon-dating research, it is likely that Alces latifrons (Broad-fronted moose; Latin name is "Cervalces latifrons" in Wikipedia, which has an outdated source of 1980 confirming this: taxonomic naming would have changed since then) was a predescessor to today's modern moose.
The closest living relative to humans is the chimpanzee.
The closest primate relative to humans is the chimpanzee.
Bears are from the family ursidae, while dogs are from canidae, making their closest relative the dingo.
Homo erectus is the closest known relative to modern humans.
The closest relative to humans in the animal kingdom is the chimpanzee.
The closest relative to the wombat is the koala.
The closest relative's to the llama is alpaca's,and camel's
The Bengal tiger is the tiger that is the closest living relative of the Amur tiger.
I would have to say the closest relative to the seahorse is the koala, since that is the category in which this question is located.
lynxes or closest relative for bobcats
The closest relative to humans besides primates is the bonobo, which is a type of great ape.
The giraffe's closest relative is the okapi.