Final answer:
Several real hominin fossils were known at the time of Piltdown's discovery, including species of Australopithecus, Homo erectus, and evidence from the Laetoli footprints. These discoveries indicated a diverse and branched evolutionary tree, contrary to what Piltdown suggested.
Step-by-step explanation:
At the time of Piltdown Man's discovery, several real hominin fossils had already been discovered. Among the known fossils were Australopithecus species, which provided the earliest evidence of bipedalism, and predates Piltdown by several million years. Additionally the fossils of Homo erectus, an ancestor of modern humans, were well-known, with discoveries in Java and China. Important discoveries also included the Laetoli footprints by Mary Leakey which were concluded to be made by Australopithecus afarensis due to their age and location. These footprints highlighted that early hominins were walking upright.
While Paranthropus fossils like Paranthropus boisei, which were not ancestral to modern humans had not been discovered at the time of Piltdown's finding it is now recognized as part of the human family tree. Lastly by the time Piltdown Man was revealed to be a hoax the field of paleoanthropology had already recognized numerous other hominin species indicating a diverse and branched evolutionary history.