Laelaps

i-67f381c77f08515a7bb29d141b70ec0f-anoiapithecus.JPG

The face of Anoiapithecus. From Moya-Sola et al. (2009).

ResearchBlogging.org One of the most controversial aspects of the whole Darwinius kerfuffle has been the primate’s proposed status as “the ancestor of us all.” The fossil, named “Ida”, has been popularly touted as the “missing link” connecting us to all other mammals, but how can we really know if Darwinius fits this role? The truth is that we can’t, and it is nearly impossible to parse direct ancestor-descendant relationships among fossil vertebrates, especially when we’re talking about a fossil that lived over 40 million years before the first hominins evolved.

Indeed, the frenzy over Ida has just been made all the more unfortunate by the announcement of a fossil primate in the journal PNAS that is much, much more closely related to us. Called Anoipithecus brevirostris, this short-faced ape was recently discovered in 11.9 million-year-old (Middle Miocene) strata in Spain. It doesn’t have a book, a flashy website, or a prime-time TV slot, but it could have some very interesting implications for the origins of our ape ancestors.

During the Miocene the earth was, to an extent, a “Planet of the Apes.” There was a greater diversity of apes occupying a much wider geographic range than living apes, so much so that paleoanthropologists have long been debating whether apes first evolved in Africa or in Eurasia (with some, including our ancestors, moving back into Africa before seven million years ago and others dispersing eastward towards the Pacific). According to the authors of the new PNAS paper, Anoiapithecus may shed some new light on this contested question.

i-68a18b43b78308c7b221eb7288ca2913-faces-comparison-apes.JPG

The profile of Anoiapithecus (top left) compared to Pierolapithecus (top right) and a virtual reconstruction of Sahelanthropus (bottom). Not to scale. From Moya-Sola et al. (2009), Moya-Sola et al. (2004), and Zollikofer et al. (2005), respectively.

If we could see a living Anoiapithecus today it would look quite a bit different from the other apes you might see at the zoo or on television. While it did have some classic ape traits like the heavy brow ridges, low forehead, and large canine teeth, what sets Anoiapithecus apart is an extraordinarily short face. Its jaws did stick out a bit in front, but much less so than is seen in living great apes like gorillas, chimpanzees, or orangutans. (See comparison below.) This contrast can also be seen when the face of Anoiapithecus is compared to another Middle Miocene fossil ape from Spain described by some of the same authors in Science in 2004, Pierolapithecus. Pierolapithecus has a face that is more similar in proportions to living great apes (and also, oddly enough, the controversial hominid Sahelanthropus), while Anoiapithecus was a flat-faced ape. (See comparison above.)

i-f2d292bbb698a9125b1a730f7592f070-faces-comparison-living-apes.JPG

The profile of Anoiapithecus (top left) compared to a drawing of a female gorilla skull (top right) and a sagittal section through the skull of a female chimpanzee (bottom). Not to scale. From Moya-Sola et al. (2009), The Dental Cosmos, and The Origin and Evolution of the Human Dentition, respectively.

Indeed, the facial features of Anoiapithecus make it starkly different from almost every other fossil ape known, but what extinct apes was it most closely related to? Unfortunately comparisons among fossil apes are limited by the fossil material available (many Miocene apes are only known from teeth and a few fragments), so even if you have a relatively complete skull or even skeleton you still have to compare it to more scrappy species and genera. This is especially problematic since the face of Anoiapithecus is so unique, but aspects of its teeth appear to make it an early hominid close to kenyapithecine apes like Equatorius and Kenyapithecus. If this hypothesis is correct, then Anoiapithecus would be an early member of the evolutionary group that presently contains us and the other great apes, the hominids.

i-df942b7a219dfbf273377cebf211c75f-anoiapithecus-evo-tree.JPG

The proposed evolutionary position of Anoiapithecus (denoted by the skull). The authors propose that it and its kin represent a part of early hominid evolution that occurred in Eurasia before some later hominids dispersed back into Africa. From Moya-Sola et al. (2009).

The hypothesis that Anoiapithecus and Pierolapithecus are part of an early hominid radiation in Europe has some interesting implications. Based upon the relationship of these two apes to earlier apes found in Europe and Africa, the authors suggest that some kenyapithecine apes left Africa, gave rise to a radiation of forms in Eurasia (like Anoiapithecus), and that some of these early hominids migrated back into Africa to give rise to the ancestors of modern African apes and humans. Anoiapithecus and Pierolapithecus would not be our direct ancestors, but rather representative of an evolutionary radiation of which our ape ancestors were a part. The picture is still a little fuzzy, but the authors feel that a few million years before the first members of our species came “Out of Africa” our more ancient ape ancestors spread back into Africa from a layover in Eurasia. (Again, it would be interesting of Sahelanthropus and Pierolapithecus had a close relationship, as this would support the dispersal of at least some apes back into Africa even if they were not the ones that gave rise to the earliest hominins).

As the authors of the study note more fossil discoveries will be essential to testing this hypothesis. While they focus on Eurasia, it would be wonderful if more complete remains of Middle Miocene apes from Africa were discovered for comparison. Nothing is written in stone yet, but if the authors of this new paper are correct, Anoiapithecus and its kin could provide important clues to the evolution of some of our ape ancestors outside Africa.

Moya-Sola, S., Alba, D., Almecija, S., Casanovas-Vilar, I., Kohler, M., De Esteban-Trivigno, S., Robles, J., Galindo, J., & Fortuny, J. (2009). A unique Middle Miocene European hominoid and the origins of the great ape and human clade Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0811730106

Comments

  1. #1 johannes
    June 3, 2009

    > During the Miocene the earth was, to an extent, a “Planet
    > of the Apes.” There was a greater diversity of apes
    > occupying a much wider geographic range than living apes,

    Strange that (non-human) apes, in spite of their intelligence and prodigious physical strength, were so thoroughly outcompeted by the cercopithecines; retaining only a pale shadow of their former glory.

  2. #2 johannes
    June 3, 2009

    > During the Miocene the earth was, to an extent, a “Planet
    > of the Apes.” There was a greater diversity of apes
    > occupying a much wider geographic range than living apes,

    Strange that (non-human) apes, in spite of their intelligence and prodigious physical strength, were so thoroughly outcompeted by the cercopithecines; retaining only a pale shadow of their former glory.

  3. #3 neil
    June 3, 2009

    Nice post Brian, it’s shame that this fossil isn’t getting more attention, I imagine the public is a bit “linked”-out.

    @Johannes I suspect that the success and spread of one particular ape might have something to do with the decline of many of the others. Certainly, that’s what is going on today.

    I’m having trouble accessing PNAS this morning, do the authors discuss potential deformation of the fossil? Indeed that profile is so extreme relative to other primates that I wonder if it has been flattened during burial. See Boyd and Motani 2008.

  4. #4 dennis
    June 3, 2009

    The face of Anoiapithecus is actually quite similar to that of the smaller Pliopithecus well-known in Europe at the same time. Pliopithecus was once thought to be a gibbon ancestor but is now widely seen as a stem catarrhine. Without post-crania it is very difficulto evaluate the new find’s phylogenetic affinities.

  5. #5 dennis
    June 3, 2009

    The face of Anoiapithecus is actually quite similar to that of the smaller Pliopithecus well-known in Europe at the same time. Pliopithecus was once thought to be a gibbon ancestor but is now widely seen as a stem catarrhine. Without post-crania it is very difficulto evaluate the new find’s phylogenetic affinities.

  6. #6 kai
    June 3, 2009

    Were any stuck silverware drawers found near the fossil?

  7. #7 Laelaps
    June 3, 2009

    Kai; I knew that one was coming sooner or later. Well done! ;)

    Neil; I’ll have to look at the paper again. I don’t recall any notes about distortion, but I could be wrong. If you can access it, though, check out the paper on the reconstruction of Sahelanthropus. IIRC when it was first announced a number of people said it was close to our ancestry because it had a flat face, but obviously it was crushed and deformed during fossilization.

    Dennis; Yes, some post-crania would be nice, but I think the authors do a good job underlining that their hypotheses are provisional in the paper itself. They also make some convincing arguments that Anoiapithecus is very similar to Pierolapithecus (from which postcrania are known) and that this new fossil has aspects of its teeth that place it among the dryopithecini. As the authors themselves note, further fossils discoveries will help resolve some of these issues.

  8. #8 neil
    June 3, 2009

    Indeed, the Sahelanthropus debate was precisely what I was thinking of.

    Now having had a chance to read, the Moya-Sola paper, I notice that they do mention deformation, at least in passing:

    “Complete eruption of the M3 indicates that IPS43000 belongs to an adult individual, because the slight displacement of this tooth from the alveolar plane merely results from bone distortion at the level of M2-M3.” (Moya-Sola et al. 2009)

    Also note that the basin this fossil is from is in an active compressional tectonic zone, bounded by a thrust fault. Looking at the pictures, it is clear that some brittle deformation has occurred, either taphonomically or through overburden or tectonic stress. Whether some plastic deformation has also occurred would seem to be an open question.

    None of this necessarily affects the interpretations made by the authors, but it’s worth a mention, especially given the heavy emphasis placed on the craniofacial angle in this paper and the morphometric approach. Again, for a good demonstration of the dangers of drawing morphological conclusions from “puzzle-pieced” fossils I highly recommend the Boyd and Motani paper I linked to in the earlier comment (full disclosure: one author is a labmate and the other my adviser, but I had nothing to do with the paper myself).

  9. #9 Adrian Thysse, FCD
    June 3, 2009

    I have an image of what Anoiapithecus may have looked like at
    http://evolvingwithdarwin.blogspot.com/2009/06/new-hominid-described.html

  10. #10 Raymond Minton
    June 4, 2009

    It would be interesting to have a time machine to travel to the Miocene, just to see apes at the peak of their diversity, with features not found in the modern world. The detail of the flat face of Anoiapthecus is interesting, because modern apes have flatter, more “humanlike” faces when they’re born, and I wonder if this is a throwback to the ancestral condition.

  11. #11 film izle
    November 27, 2010

    Yes, some post-crania would be nice, but I think the authors do a good job underlining that their hypotheses are provisional in the paper itself.

  12. #12 jose jockson
    February 27, 2011

    fuckin bitch

The site is undergoing maintenance presently. Commenting has been disabled. Please check back later!