The answer greatly depends on the strictness of the definition of “undiscovered.”

For instance, in 2006, a hybrid of grizzly bear and polar bear was discovered (defined as “shot” in this case). While this hybrid was interesting, it wasn’t entirely surprising since both grizzly bears and polar bears were already known. Additionally, there were a few unconfirmed reports and documented hybridization in zoos. Therefore, the 2006 discovery simply confirmed the existence of these hybrids in the wild.

Another example is the identification of the Tapanuli orangutan in 2017. Although this species was documented by Dutch naturalists back in 1939, it wasn’t initially recognized as a distinct species separate from the Sumatran orangutan, which it closely resembles. So, this was more of a reclassification than a pure discovery.

The kabomani tapir from the Amazon is another similar case. It was already known but wasn’t classified as a separate species until 2013. There’s also a debated giant peccary in Brazil that may or may not be a distinct species.

If we exclude hybrids of well-known and closely related species and known animals that were reclassified as separate species, we come to the saola or Vu Quang ox. This animal was first documented in scientific literature based on remains found in 1992. The saola is particularly unique because it has no closely related species or hybrids. It is the only species in its genus, Pseudoryx, which also stands apart distinctly from other bovids.

The discovery of such a large animal (about five feet long and three feet high) in a separate and distinct genus was quite surprising and widely reported. However, the discovery wasn’t entirely pure, as the native Hmong people in the Annamite mountain range of Vietnam and Laos already knew about the saola.

Similarly, the Burmese snub-nosed monkey, also known as the sneezing monkey, was unknown to zoologists until 2010 but already known to the Lisu people of northern Myanmar. Can we consider an animal undiscovered if knowledge of it hasn’t spread beyond a local culture that doesn’t regularly contribute to scientific research?

Regarding large land animals truly seen by humans for the first time, unfamiliar to locals as well, the most recent discovery might be the megamouth shark, first found in 1976. This shark is not only rare but also a deepwater species, making it well-hidden from human observation.

Therefore, while there may be unknown land animals larger than humans, it is more likely that undiscovered megafauna would be deep-sea creatures rather than land animals. For land animals, there could still be megafauna unknown to zoologists, but it is highly probable that they would already be familiar to local communities (like the saola) or classified as hybrids or extremely close relatives of known species (like the tapanuli orangutan).

To explore a comprehensive list of megafauna discovered in modern times, organized by the date of discovery, you can refer to the Wikipedia page “List of megafauna discovered in modern times.” Each discovery on the list provides a link to more detailed information.

I hope this answers your question!