Laelaps

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A Cuban crocodile (Crocodylus rhombifer), photographed at the National Zoo in Washington, DC.

ResearchBlogging.org

No one knew what happened to William Olson. At about three in the afternoon on April 13, 1966 he had been swimming with his friends from the Peace Corps in the part of the Baro river that ran through Gambela, Ethiopia when he suddenly disappeared. The last person to remember seeing him was hunter Karl Luthy. One moment Olson was standing in the river, pressing his body against the current, and the next he was gone.

Luthy could not be sure, but he was almost certain that Olson had been taken by a Nile crocodile. He and the people who lived in the nearby village had warned the young travelers that swimming in the river was dangerous, especially since a child and a woman had been recently devoured by a crocodile there, but the American visitors did not care. Luthy’s fears were confirmed about a half hour after attack. Just at the edge of sight the crocodile appeared with Olson’s body in its jaws, but rather than go after the animal right away Luthy decided to wait until morning. Rushing to kill the reptile would do no good. Olson was already dead, and if Luthy attempted to shoot to crocodile while it was still in the river both the animal and Olson’s body might be lost. Instead he decided to leave the predator be until morning when it came out of the water to bask in the sun.

The crocodile did just as Luthy predicted. It hauled itself out onto the riverbank at about seven the next morning, and after a few attempts Luthy and his client were able to kill it. When they opened it up there could be no doubt that the thirteen-foot long crocodile was the one that had killed Olson. What was left of the young man was placed in a cardboard box.

Such tragic events remind us that we are not separate from or above nature. Much like our hominin forebears we can still be prey, and crocodiles are among the animals that have long considered us to be on the menu. Fragmentary remains of fossil hominins from the famous locality Olduvai Gorge, especially, show tell-tale signs that crocodiles consumed the bodies of our ancient relatives, and new fossils from the 1.8 million year old rocks there have identified one of the possible culprits.

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A restoration of a Nile crocodile skull (top) compared to a preliminary restoration of a C. anthropophagus skull based upon available evidence.

For years it had been assumed that the Olduvai crocodiles were prehistoric representatives of the Nile crocodiles (Crocodylus niloticus) that still occasionally snatch people from the water’s edge, but when crocodile expert Chris Brochu looked at numerous fragments collected by Jackson Njau and Robert Blumenschine he realized that the Olduvai croc was something quite different. Even though he had only a collection of fragments to work with the paleontologists could tell that this ancient reptile had a deeper snout than its living relative, and the back of its skull was flared up into “horns” of bone that would have given it a unique profile somewhat reminiscent of living Cuban crocodiles (Crocodylus rhombifer). This prehistoric croc would have dwarfed all but the largest of its living relatives, though. Estimated at a maximum length of approximately 25 feet long it would have been a truly frightening ambush predator, and given the tooth-marked hominin bones the the trio of scientists decided to name it Crocodylus anthropophagus in the journal PLoS One.

Clearly C. anthropophagus was large enough to kill and consume hominins, but did it really do so? To approach an answer we have to split this question into two. From the fossil evidence collected so far it is clear that some prehistoric crocodiles at Olduvai consumed the bodies of hominins. Tooth marks on hominin bones confirm this beyond reasonable doubt.

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Lower jaw fragments of the newly-named crocodile Crocodylus anthropophagus. From the PLoS One paper.

The question is whether individual C. anthropophagus killed the hominins in the first place. On this point there is no evidence to discuss. It is certainly plausible that C. anthropophagus counted early humans as prey but given the present lack of direct evidence actual predation is difficult to confirm. Even so it is remarkable that we have any evidence that these crocodiles fed on hominins at all. Large C. anthropophagus individuals probably would have pulverized hominin bodies prior to consumption, and once the flesh and bones of the early humans entered the crocodile’s stomach they would be eaten away by powerful stomach acids. (As the authors suggest this means that smaller crocodiles fed upon the hominins represented by the tooth-marked bones.) If hominins fell prey to fully-grown crocodiles it is unlikely that any trace would have been left behind.

These caveats aside I do think it is likely that C. anthropophagus at least occasionally fed on hominins. Given the projected size of the crocodile, the habits of its living relatives, and the tooth-marked bones I do not think that a C. anthropophagus would not have much hesitation about gobbling up an unwary hominin if the opportunity presented itself. While we might consider Olduvai to be one of the cradles of our ancestors, a place where stone tools were invented and utilized, 1.8 million years ago the human inhabitants of that place were still prey.

[The account of Olson's death was summarized from a fuller account given in the book Eyelids of Morning: The Mingled Destinies of Crocodiles and Men]

Brochu, C., Njau, J., Blumenschine, R., & Densmore, L. (2010). A New Horned Crocodile from the Plio-Pleistocene Hominid Sites at Olduvai Gorge, Tanzania PLoS ONE, 5 (2) DOI: 10.1371/journal.pone.0009333

Comments

  1. #1 Jared
    February 24, 2010

    nice write-up, I started reading the paper a few hours ago, but got side-tracked by this one:
    http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0009117

  2. #2 DDeden
    February 24, 2010

    Have any C. anthropophagy bones been found with cut-marks by stone tools? Presence of crocs would seem a good reason to make weapons, especially sharp jabbing spears, (and possibly later, bait-traps of hand-axes/flakes inserted into hunks of meat or fish).

  3. #3 Hai~Ren
    February 24, 2010

    Great write-up, Brian.

    It’s interesting to note that this species appears to be based on remains that were once referred to Rimasuchus, which is an osteolaemine related to the extant dwarf crocodiles Osteolaemus. I think this photo on Tetrapod Zoology is that of a Crocodylus anthropophagus skull at Koobi Fora. (Note that it was labelled as Rimasuchus).

    Crocodilians really seem to have been quite diverse during the Miocene, Pliocene and Pleistocene, and included quite a few gigantic forms. The paper raises interesting questions about the evolution of Crocodylus, its origins and how the genus spread throughout the tropics. I would guess that the tendencies of several species to live in coastal areas and to even make sea crossings may have been a factor in dispersal. It certainly is quite an intriguing issue, especially with regards to competition between Crocodylus and any native crocodilians in the continents they arrive in. Wherever Crocodylus arrived, they must have competed and interacted with the native crocodylids, alligatorids, and the gavialids (which were much more diverse back then and also included many seagoing forms then).

    The 25 or so crocodilian species we have today are just a pale shadow when you think about all those that became extinct relatively recently, possibly during the Holocene, including the mekosuchines, Aldabrachampsus and Voay.

  4. #4 Bill
    February 25, 2010

    And if anyone hasn’t read Eyelids of Morning yet and been blown away by the Peter Beard photos…well, you have a treat in store

  5. #5 nancy brownlee
    February 26, 2010

    Talk about yer Darwin Awards… what sort of person, informed that a lurking crocodile has recently killed and eaten two people in the immediate area, thinks, “Oh, who cares. I’m going swimming anyway.” A stupid person, that’s what kind.
    Crocodiles, and alligators, and all their closely related toothy reptile kin, eat everything they can catch. The eat birds, turtle, muskrats, nutria, dogs, cats, coyotes, water buffalo, small hippos, cows, goats, horses, zebras… and people. We know this. We have films. When an animal comes to the water to drinks, a croc grabs its snout or head or neck or leg, and that’s all she wrote. There’s some kind of mystery about the diets of giant prehistoric crocodiles? Maybe they were gathering mangoes? I’m not understanding the question, here.

  6. #6 Assefa Bekele
    March 14, 2010

    I remember Mr William Olson. I was his student in year 8 at Medhane Alem High School in Addis Ababa, Ethiopia. He was teaching us a Set Theory in Mathematics.

    Mr Olson was a very active and funny young man. I never forget a nickname he gave me in my class.

    He thought us math on Friday before lunch and on Monday morning when arrived at the school, the bad news was announced to us. It was a very sad day. We all were shocked by the incident.

    It is amazing that after all those years (almost 44 years), Yahoo. alerted me and this case came onto my computer.

  7. #7 film izle
    November 27, 2010

    Clearly C. anthropophagus was large enough to kill and consume hominins, but did it really do so? To approach an answer we have to split this question into two. From the fossil evidence collected so far it is clear that some prehistoric crocodiles at Olduvai consumed the bodies of hominins. Tooth marks on hominin bones confirm this beyond reasonable doubt.

  8. #8 Mike Walley
    January 3, 2011

    Nicely written article linking tragedies that still occur today, with what might have befallen our ancestors and indeed other species of hominid. Although the fossil record is open to interpretation and the direct evidence is a little questionable, I think given hominids reliance on water sources it is likely that such attacks did take place. Certainly, this new species of crocodylus would seem very capable of making such an attack.

  9. #9 seslisohbet
    February 26, 2011

    record is open to interpretation and the direct evidence is a little questionable, I think given hominids reliance on water sources it is likely that such attacks did take place. Certainly, this new species of crocodylus