Zoologist, media consultant, and science writer, Dr Karl Shuker is also one of the best known cryptozoologists in the world. He is the author of such seminal works as Mystery Cats of the World (1989), The Lost Ark: New and Rediscovered Animals of the 20th Century (1993; greatly expanded in 2012 as The Encyclopaedia of New and Rediscovered Animals), Dragons: A Natural History (1995), In Search of Prehistoric Survivors (1995), The Unexplained (1996), From Flying Toads To Snakes With Wings (1997), Mysteries of Planet Earth (1999), The Hidden Powers of Animals (2001), The Beasts That Hide From Man (2003), Extraordinary Animals Revisited (2007), Dr Shuker's Casebook (2008), Karl Shuker's Alien Zoo: From the Pages of Fortean Times (2010), Cats of Magic, Mythology, and Mystery (2012), Mirabilis: A Carnival of Cryptozoology and Unnatural History (2013), Dragons in Zoology, Cryptozoology, and Culture (2013), The Menagerie of Marvels (2014), A Manifestation of Monsters (2015), Here's Nessie! (2016), and what is widely considered to be his cryptozoological magnum opus, Still In Search Of Prehistoric Survivors (2016) - plus, very excitingly, his first two long-awaited, much-requested ShukerNature blog books (2019, 2020).

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Friday 8 February 2013


This photograph of a shot Bili ape appeared in Vol. 1 of Adolf Friedrich Herzog von Mecklenburg’s tome Vom Kongo zum Niger und Nil: Berichte der Deutschen Zentralafrika-Expedition 1910/1911, which was published in 1912 – more than a century before this highly distinctive ape form’s reality was formally recognised by science

Here's the latest in my occasional series of ShukerNature cryptozoology articles re anomalous and controversial chimpanzee forms (click here for my account of the pygmy chimpanzee or bonobo, here for the koolookamba, here for Ufiti, and here for 'apeman' Oliver).

Until quite recently, even amid the many remote regions of darkest Africa, the possibility of an unknown form of anthropoid existing there yet still eluding scientific recognition seemed ludicrous - but then came the Bili (aka Bondo) ape.

The saga of this remarkable, highly controversial primate began more than a century ago, when in 1898 a Belgian army officer returned home from what is now the Democratic Republic of Congo with some gorilla skulls obtained by him in a forested region near the village of Bili, on the Uele River in northern Congo's Bondo area - even though no other gorillas had been found within hundreds of miles of Bili before (or since). He donated them to Belgium's Congo Museum in Tervueren, where in due course they were examined by its curator, Henri Schouteden. He was sufficiently struck by their anatomical differences from other gorilla skulls as well as by their unique provenance (roughly halfway between the extreme edges of the western and eastern distribution of any gorilla populations) to classify them as a new subspecies of gorilla, which he dubbed Gorilla gorilla uellensis.

Less convinced of their separate taxonomic status, conversely, was mammalogist Prof. Colin Groves, whose examination of these skulls in 1970 led him to announce that they were indistinguishable from western lowland gorillas. Thereafter, the Bili ape sank back into obscurity - until 1996, when Kenyan-based conservationist and wildlife photographer Karl Ammann, intrigued by its strange history and apparent disappearance, set out on the first of several Congolese quests to rediscover this mysterious primate.

And rediscover it he did, bringing back such compelling evidence for its presence that several other notable investigators launched their own searches, and returned with equally fascinating clues concerning the Bili ape's nature. Such researchers included primatologist Dr Shelly Williams from Maryland's Jane Goodall Institute, Dr Richard Wrangham from the Leakey Foundation, Dr Christophe Boesch from Leipzig's Max Planck Institute for Evolutionary Anthropology, Dr Esteban Sarmiento from New York's American Museum of Natural History, and Dr George Schaller from New York's Wildlife Conservation Society.

What made their various finds so especially interesting was the ambivalent identity that they collectively yielded for the Bili ape - because, uniquely, it deftly yet bemusingly combines characteristics of gorillas with those of chimpanzees, creating a shadowy anthropoid that is at once both yet neither. For instance: if the Bili ape is a chimpanzee, it is a veritable giant, because videos of living specimens and photographs of dead ones suggest a height of 5-6 ft - a mighty stature supported by the discovery of enormous footprints, some measuring almost 14 in long, and therefore nearly 2 in longer even than those of the mountain gorilla!

A dead Bili ape, revealing its noticeably large size (http://www.factzoo.com/mammals)

Also, very large ground nests constructed by Bili apes have been found that compare with those created by gorillas; normal chimps build smaller, tree-borne nests. Further evidence of the Bili ape's great size comes from local Bondo hunters, who distinguish two distinct apes - 'tree-beaters' (normal chimps) and 'lion-killers' (the Bili apes). The latter earn their name from their combined size and ferocity, a mix potent enough to ensure their terrestrial safety even in a jungle profusely populated by lions and leopards.

Indeed, so unafraid of these great cats are the Bili apes that according to media claims they hoot loudly when the moon rises and sets - an activity unknown among normal, smaller chimps, who avoid doing so in case they attract predators. However, these latter claims have been denied by Amsterdam University field researcher Cleve Hicks, who spent a year with colleagues tracking Bili apes during from mid-2005 to June 2006, followed by a second study spanning July 2006-February 2007.

Particularly noticeable is the presence of a pronounced sagittal crest running along the top of one of the original skulls collected by the Belgian army officer, and also on a Bili ape skull found by Ammann in 1996 - because this crest, normally an indication of powerful jaws as the jaw muscles are attached to it, is characteristic of gorillas, not of chimps. Conversely, the facial anatomy of the Bili skulls is decidedly chimp-like, not gorilla-like. In addition, hair samples taken from Bili ape ground nests have been shown to contain mitochondrial DNA similar to that of chimps, and the fruit-rich content of examined faecal droppings is again consistent with a chimp identity - although, perplexingly, the droppings themselves outwardly resemble those of gorillas.

So what is the Bili ape - a gorilla-sized chimp (freak population?/new subspecies?/new species?), an aberrant form of gorilla (freak population?/new subspecies?/new species?) that has evolved certain chimp-like anatomical and behavioural characteristics, or even possibly a genuine chimpanzee-gorilla hybrid? No confirmed crossbreeding between chimp and gorilla has ever been recorded, but the two species are sufficiently similar genetically to engender viable offspring. Mitochondrial DNA is passed down exclusively from the maternal parent, so if such interspecific matings are indeed occurring they must involve female chimps and male gorillas, to explain why the mitochondrial DNA from the Bili ape samples is chimp-like.

Happily, however, the Bili ape's identity was eventually unmasked. Comprehensive DNA analyses, including nuclear DNA (thus shedding light on both the maternal and the paternal lineages of the Bili ape), had been underway since autumn 2003 at Omaha's Henry Doorly Zoo, under the auspices of conservation geneticist Dr Ed Louis, and involving DNA comparisons with gorillas, chimps, and also bonobos (pygmy chimps).

So too had analyses of mitochondrial DNA taken from faecal samples conducted by Dr Cleve Hicks and other Amsterdam University colleagues, who had also examined these primates' behaviour in the field. And in 2006, this latter team announced that their findings all confirmed that the Bili ape belongs to a known subspecies of chimp – the eastern chimpanzee Pan troglodytes schweinfurthii. Presumably, therefore, the Bili ape's very distinctive morphological features have evolved through its population's isolation from others of this subspecies but involve relatively little change at the genetic level. After years of mystery and intrigue, the riddle of the Bili ape had at last been solved.

This ShukerNature post is excerpted from my book The Encyclopaedia of New and Rediscovered Animals (Coachwhip: Landisville, 2012).


  1. This is still a very interesting discovery, that simple geographical isolation could produce such a radically different form of a known species! I'm still reading and still love the book, by the way!

  2. I believe this ape was mentioned in the Tarzan series but was discounted as fiction for years. It wasn't until this ape was rediscovered that they decided he described the bili ape.

  3. Very interesting piece, Dr Shuker! Quick question: do other chimps exhibit the sagittal crest?

  4. @How31rd - interesting! Thanks for the info.

    @Capt Steve - Glad you enjoyed it. Sagittal crests only occur very rarely in chimps (another reason why the Bili specimens are so special), and normally only in male specimens.

  5. Alas Karl if only that village'd been called James then we'd've never've forgotten the James Bondo ape.

    And the proof of that's from the day it was discovered right upto the present all Seventies West Ham Utd fans still revere the hairy beast known as Bili Bondo.

    ps I'm actually an LFC fan.

  6. Hey Dr. Shuker, I was reading your book today and I have a question. Was the giant macaque, that one of the types of "Yeren" was identified as, a new species? If so, could you please tell me where I could find some information on this? Thanks.

    1. Hi Jay, No, as yet it has not been formally described as a new species.

  7. Hello, Dr. Shuker. I would like to know what the current status is about your new and updated version of In Search of Prehistoric Survivors. You see, I have that book, and I love it very much. However, since it was published in 1995, I have noticed that the palaeontological information in it is a little outdated by now. Therefore, a 2nd edition would be absolutely amazing!

    Also, I have noticed that, back in 2009, you mentioned that it would be published in 2010. However, that apparently did not happen, though. So, what is the current status on that book? Will it ever be published? Thanks!

  8. My initial plan for In Search of Prehistoric Survivors was to prepare a fully updated version, but it has proven a much greater task to do than I'd planned. Consequently, I subsequently decided it would be best to republish the original edition (from 1995), but this time in full colour with lots of new illustrations, so that at least it would be back in print, so this is what will be happening later this year. It may contain a limited amount of new info - I haven't decided yet, but I will keep everyone informed as to its progress and nature.

    1. Awesome, I've always been interested in rumors of a new version of that book! In fact, that's the reason I had first contacted you a while ago. I can't wait.

  9. I haven't given up on the idea of a full updated new edition, however, and I hope to have one completed within the next three years or so.

  10. Obviously, it will not merely update the cryptozoological content but also the palaeontological content, and will emphasise the often overlooked but crucial point that if any of the cryptids in the book are truly prehistoric survivors, they will be the product of many millions of years of continuing evolution, i.e. from the age when the most recent known fossils were produced to right up to the present day. Consequently, they may well be very different morphologically and physiologically from their palaeontological predecessors, which in turn means that direct comparisons between modern sightings and fossil evidence has only limited value. The best example of this is to look at the limited diversity of mammals 65 million years ago, and then compare that with the huge diversity of mammals alive today. Just by looking exclusively at 65-million-year-old fossil mammals remains, would it truly be possible to predict the existence 65 million years later of mammals as diverse as bats, whales, lions, antelopes, rats, kangaroos, platypuses, monkeys, and armadillos, for instance?

  11. Redmond O'Hanlon in his book 'Congo' describes an ape that is bigger than a chimp, but it is not a gorilla, and it is white, according to what the locals told him. Would that be a relative of the Bili ape? It is 'only' about four hundred miles west of Bili.
    Other thing: the potbelly on the dead Bili ape reminds me of a gorilla.

  12. If these apes coexist with chimpanzees, it seems unlikely they're chimps themselves.
    I accept there've been DNA tests confirming their identity as chimps but it still seems weird.
    The locals appear to differentiate a kind of ape that's not a gorilla, from a chimp-lion killers vs tree beaters.
    The lion-killers are different behaviourally and morphologically from chimpanzees, forming separate populations even though their range overlaps, yet the DNA shows them to be chimps?
    I'm still confused, though intrigued.

  13. I am beyond speechless... This is an amazing discovery...

  14. This is very interesting but it is perturbing that people seem to have thought that they can kill these creatures with such abandon.Surely our attitude towards the preservation of these creatures should be the same as that we have towards gorillas.

  15. One of the issues I have with the billi ape being a separate troglodyte species is the argument put forward that its size is greater than normal Chimps. Given the know small stature of the jungle people holding it up in the 1st photograph and the second photo of similarly small people in the background behind the deceased specimen, it seems to me over reach to suggest the ape is therefore larger than normal chimps.

  16. My new Ted X talk on the cultural behavior of the Bili apes: https://www.youtube.com/watch?v=nt0YXZBvAZE&t=168s

  17. Karl great article, the sagittal crest reminds me of Bigfoot here (witnesses observe this in many BF sightings) and I wish you could educate creationists about Evolution. I love your books and blog here and wish you'd do a Zoology textbook or book with Cryptid highlights someday.

  18. If there were two kind of chimps it seems odd to me that they were only a subspecies of chimp. The 'lion kill' chimp is a really big beast, it should be better investigated IMO.