Meganthropus is an extinct group of pongine hominid apes known from the Pleistocene era in Indonesia. Fossils of this genus were discovered at the Sangiran site near Surakarta in Central Java, Indonesia. These fossils include large jaw and skull fragments, as well as several isolated teeth. The classification of Meganthropus has a long and complicated history. The original fossils were first named as a new species, Meganthropus palaeojavanicus, but for many years, the genus name was not officially recognized and was used informally to describe the fossils.

In the mid-2000s, scientists were unsure how to classify the fossils. Most paleoanthropologists thought the specimens might be related to Homo erectus. However, other scientists used names like Homo palaeojavanicus and Australopithecus palaeojavanicus, showing the uncertainty about their classification.

In 1948, a robust skull found at Swartkrans (SK48) was briefly called Meganthropus africanus. This specimen is now officially known as Paranthropus robustus, and the earlier name Meganthropus africanus is no longer used because it is a junior synonym. Some fossils from Meganthropus were found alongside evidence of tools similar to those made by Homo erectus, which is why Meganthropus was sometimes linked to Homo erectus as H. e. palaeojavanicus. In 2019, a study of tooth shapes confirmed that Meganthropus is a valid genus of non-hominin hominid ape, most closely related to Lufengpithecus.

Fossil finds

The number of fossil finds has been relatively small, and it is a distinct possibility that they are a paraphyletic assemblage. Due to this, they will be discussed in detail separately.

This large jaw fragment was first found in 1941 by Gustav von Koenigswald. Koenigswald was captured by the Japanese in World War II, but managed to send a cast of the jaw to Franz Weidenreich. Weidenreich described and named the specimen in 1945, and was surprised by its size, as it was the largest hominid jaw then known. The jaw was roughly the same height as a gorilla’s, but had a different shape. In most anthropoids, the mandible is tallest where the two sides of the lower jaw meet. However, in Sangiran 6, the greatest height is seen near the position of the first molar (M1).

Weidenreich considered acromegalic gigantism, but ruled it out because the jaw did not have typical features such as an exaggerated chin or small teeth compared to its size. Weidenreich did not estimate the size of the hominid directly, but said it was two-thirds the size of Gigantopithecus, which was twice as large as a gorilla. If scaled similarly to a robust human or erect hominid, this would make the hominid about 8 feet (2.44 m) tall and weigh approximately 400 to 600 lbs (181–272 kg). In his book Apes, Giants, and Man, Weidenreich wrote about the jawbone.

The jawbone was used in part of Grover Krantz’s skull reconstruction, which was only 21 cm (8.3 in) tall.

Another jaw fragment was described by Marks in 1953. It was similar in size and shape to the original mandible but was also severely damaged. Recent work by a Japanese/Indonesian team repaired the fossil, which was from an adult. This specimen was smaller than known specimens of Homo erectus. Interestingly, it retained some traits unique to the first mandible find and not seen in Homo erectus. No size estimates have been made yet.

This jaw fragment was discovered in 1979 and shares some features with earlier mandible finds. Its connection to Meganthropus appears weak compared to other mandible discoveries.

This mandible and ramus were acquired by Sartono in 1993 and dated to between 1.4 and 0.9 million years ago. The ramus portion is badly damaged, but the mandible fragment is relatively intact, though details of the teeth are lost. It is slightly smaller than Meganthropus A and very similar in shape. Sartono, Tyler, and Krantz agreed that Meganthropus A and D were likely representations of the same species, regardless of what it is.

Tyler described this specimen as a nearly complete but crushed cranium within the size range of Meganthropus and outside the (assumed) range of Homo erectus. The specimen had a double temporal ridge (sagittal crest), which almost met at the top of the cranium, and a heavily thickened nuchal ridge.

This skull fragment was first described by Sartono in 1982. Tyler’s analysis concluded it was outside the normal range of Homo erectus. The cranium was deeper, lower vaulted, and wider than any previously found. It had a double sagittal crest or double temporal ridge and a cranial capacity of about 800–1000cc. Since its presentation at the AAPA meeting in 1993, Tyler’s reconstruction of Sangiran 31 has been accepted by most experts.

Like most fossils, this one was heavily damaged. However, the completeness of the post-facial cranium makes errors in reconstruction unlikely. Tyler’s accepted reconstruction of Sangiran 31 shows a double temporal ridge. The temporal muscles extend to the top of the parietal bone, almost joining there. No other Homo erectus specimens show this trait. Krantz’s reconstruction of Sangiran 31 as a giant Homo habilis has been questioned by other experts.

This is another fossil with weak ties to Meganthropus. It appears to be the posterior part of a hominid cranium, measuring about 10 to 7 cm. Tyler (1996) described it and found that the whole cranium’s occipital angle was likely about 120°, which would be outside the known range of Homo erectus. Homo erectus has a more angled occiput. However, other experts have questioned Tyler’s interpretation, including doubts that the fragment was actually the part of a skull he believed it to be.

Scientific interpretation

Most scientists who study ancient humans believe the Meganthropus fossils belong to the same group as H. erectus. Kaifu et al. (2005) explained that if all early Homo populations from Africa that are clearly different from earlier forms are considered H. erectus, then the Grenzbank/Sangiran group would be part of an earlier group within this species. However, some scientists argue that Meganthropus fossils should be classified as a separate species or a subspecies of H. erectus, suggesting names like H. palaeojavanicus or H. e. palaeojavanicus. These scientists base their argument on traits such as smaller brain size, as noted by Tyler (2001). In contrast, Wolpoff (1999) pointed out that earlier and later Javanese fossils share many similarities, which suggests no need to classify them as separate species or subspecies.

Robinson (1953) first proposed that Meganthropus, based on a jawbone fragment from Sangiran 6, might be a type of robust australopithecine found in Southeast Asia. Krantz (1975) later suggested that the Sangiran 6 jawbone is too large to belong to H. erectus and should instead be classified as Australopithecus africanus, a more slender type of australopithecine. Koenigswald (1973) noted that the jawbone of Meganthropus shows traits of both robust and slender australopithecines, such as features similar to A. africanus (premolars) and A. robustus (size).

A study by Orban-Segebarth & Procureur (1983) concluded that the Sangiran 6 jawbone has traits similar to australopithecines. However, Kramer and Konigsberg (1994) disagreed with this view. Cartmill and Smith (2009) stated that there is no strong evidence to classify any Meganthropus fossils outside of H. erectus.

The idea of a "mystery ape" closely related to Lufengpithecus in the Javan Pleistocene was first proposed by Russell Ciochon in 2009, though he still believed Meganthropus was the same species as H. erectus. A 2019 study on tooth shapes found that Meganthropus is a valid, distinct genus of non-human hominid ape, different from Pongo (orangutans) and Homo. This study also showed Meganthropus is most similar to Lufengpithecus, meeting the criteria for the "mystery ape." The name "Pithecanthropus dubius" was found to be an older, less official name for the same group.