Among animals, the false killer whale wins the prize. Up to 20 feet long (6m). First described by British paleontologist and biologist Richard Owen in his 1846 book, A history of British fossil mammals and birds, based on a fossil skull discovered in 1843. Discovered in the wild when carcasses washed up on the shores of Denmark in 1861. Now a near-threatened species, one step removed from a species of least concern.
Bonus:
the Okapi, also known as the forest giraffe, the okapi is a blend of a zebra, donkey, deer, and antelope. Yet, its closest genetic link is giraffes. Europeans in the 18th and 19th centuries called this animal the “African Unicorn.”
This article is a little credulous, but it lists actual examples of living species.
The TV show Extinct or Alive with Forrest Galante looks for potentially extinct species to see if there are still living specimens. On one episode they rescued a single presumed extinct tortoise from an island allegedly at risk of a volcanic eruption.
Yes. There were two seasons, with 18 episodes total. Per Wikipedia: “The series has been involved in the possible rediscovery of eleven animals, namely the Zanzibar leopard, the Pondicherry shark, the Fernandina Island Galápagos tortoise, the Miller’s grizzled langur, the Cape lion, the Malagasy hippopotamus, the Yangtze giant softshell turtle, Rio Apaporis caiman, Whitetip weasel shark, Ornate sleeper-ray and the Flapnose houndshark.”
I am not sure if any of those fit the requirement of “largest re-discovered animal”, but themapleleaf might find them interesting.
Sure, if anyone wants to post further examples that don’t exactly fit my original criteria, you might as well. These other examples are also interesting.