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East-African apiths ate papyrus sedges ?

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  • Marc Verhaegen
    http://www.pnas.org/content/early/2012/11/07/1204209109.abstract Isotopic evidence for an early shift to C4 resources by Pliocene hominins in Chad Julia
    Message 1 of 1 , Nov 18, 2012
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      http://www.pnas.org/content/early/2012/11/07/1204209109.abstract

      Isotopic evidence for an early shift to C4 resources by Pliocene hominins
      in Chad
      Julia Lee-Thorp, Andossa Likius, Hassane Mackaye, Patrick Vignaud, Matt
      Sponheimer & Michel Brunet 2012
      PNAS doi 10.1073/pnas.1204209109


      Foods derived from C4 plants were important in the dietary ecology of
      early Pleistocene hominins in S- & E-Africa, but the origins & geographic
      variability of this relationship remain unknown.
      Carbon isotope data show that Au.bahrelghazali are >3 Ma, the results
      extend the pattern of C4 dependence seen in Par.boisei in E.Africa by >1.5
      My.
      The Koro Toro hominin fossils were found in argillaceous sandstone levels,
      along with abundant grazing & aquatic faunal elements that, in
      combination, indicate the presence of open to wooded grasslands & stream
      channels associated with a greatly enlarged Lake Chad.
      In such an environment, the most abundant C4 plant resources available to
      Au.bahrelghazali were grasses & sedges, neither of which is usually
      considered as standard great ape fare.
      The results suggest an early & fundamental shift in hominin dietary
      ecology that facilitated the exploitation of new habitats.

      _____

      (Argillaceous minerals may appear silvery upon optical reflection, they
      contain substantial amounts of clay-like components. Greek ἄργιλλος =
      clay.
      Argillaceous components are fine-grained (<2 µm) alumino-silicates, and
      more particularly clay minerals such as kaolinite,
      montmorillonite-smectite, illite & chlorite.
      Claystone & shales are thus predom.argillaceous.
      The adjective "argillaceous" is also used to define rocks in which clay
      minerals are a secondary but significant component, eg, argillaceous
      limestones are limestones consisting predom.of calcium carbonate, but
      including 10-40 % of clay minerals: such limestones, when soft, are often
      called marls.
      Argillaceous sandstones are sandstones consisting primarily of quartz
      grains, with the interstitial spaces filled with clay minerals.)



      AFAIK lowland gorillas are among the few primates that do eat sedges
      (Hapalemur?).
      Grasses are unlikely (different enamel microwear) but aquatic vegetation
      (incl.sedges?) can explain the glossy polishing of afarensis etc enamel
      (cf papers of P-F.Puech).

      Lee-Thorp cs's findings once more corroborate my view (Hum.Evol.papers)
      that most or all East-African apiths might be closer relatives of Gorilla
      than of Homo or Pan, and that they lived in wetlands, bais, reedbeds,
      lagoons (eg, Chesowanja) & papyrus swamps (eg, Olduvai), where they partly
      fed on floating vegetation (cf AHV aquatic herbaceous vegetation in
      lowland gorilla diet).

      --marc

      ____

      From Marc Verhaegen & Pierre-François Puech 2000
      Human Evolution 15: 151-162
      "Hominid Lifestyle and Diet Reconsidered:
      Paleo-Environmental and Comparative Data"

      §
      Lukeino KNM-LU 335
      “pre-australopithecine”: ‘The red beds seems to contain marginal
      lacustrine deposits as indicated by the presence of algal mats and
      lacustrine bivalves (including complete specimens with valves in the
      closed position)’ (Pickford 1975).
      §
      Tabarin KNM-TH 13150
      “pre-australopithecine”: ‘The fauna includes aquatic animals such as
      molluscs, fish, turtles, crocodiles, and hippotami, along with others that
      might be found in the vicinity of a lake of river’ (Ward & Hill 1987).
      §
      Kanapoi KNM-KP 29281 Au.anamensis: Fish, aquatic reptiles, kudus and
      monkeys are prevalent. ‘A wide gallery forest would have almost certainly
      been present on the large river that brought in the sediments’ (Leakey cs
      1995).
      §
      Chad KT 12 A.cf.afarensis: ‘The
      non-hominid fauna contains aquatic taxa (such as Siluridae, Trionyx, cf.
      Tomistoma), taxa adapted to wooded habitats (such as Loxodonta, Kobus,
      Kolpochoerus) and to more open areas (such as Ceratotherium, Hipparion)
      […] compatible with a lakeside environment’ (Brunet cs 1995).
      §
      Hadar, Afar Locality:
      ‘Generally, the sediments represent lacustrine, lake margin, and
      associated fluvial deposits related to an extensive lake that periodically
      filled the entire basin’ (Johanson cs 1982)
      §
      Hadar AL.333 A.afarensis: ‘The bones were found in swale-like features […]
      it is very likely that they died and partially rotted at or very near this
      site […] this group of hominids was buried in streamside gallery woodland’
      (Radosevich cs 1992).
      §
      Hadar AL.288 gracile A.afarensis: Lucy lay in a small, slow moving stream.
      ‘Fossil preservation at this locality is excellent, remains of delicate
      items such as crocodile and turtle eggs and crab claws being found’
      (Johanson & Taieb 1976).of large perennial river and alluvial fan
      deposits, amid water- and reedbucks (Walker cs 1986).
      §
      Lake Turkana: ‘The lake margins were generally swampy, with extensive
      areas of mudflats […] Au.boisei was more abundant in fluvial environments,
      whereas Homo habilis was rare in such environments […] Australopithecus
      fossils are more common than Homo both in channel and floodplain deposits.
      The gracile hominids […] seem to be more restricted ecologically to the
      lake margin than are the robust forms’ (Conroy 1990).
      §
      Ileret A.boisei: ‘the fossil sample reflects climatic and ecological
      environmental conditions differing significantly from those of the present
      day. At Ileret, 1.5 Myr ago, climatic conditions must have been cooler and
      more humid than today, and more favourable to extensive forests […] The
      prominence of montane forest is particularly striking […] dominated by
      Gramineae and Chenopodiaceae appropriate to the margins of a slightly
      saline or alkaline lake’ (Bonnefille 1976).
      §
      Konso A.boisei: ‘The highly fossiliferous sands at the mid-section of
      KGA10 are interpreted to be the middle to distal portions of an alluvial
      fan, deposited adjacent to, and extending into, a lake. Fossils and
      artefacts deriving from horizons of sands and silts are not abraded and
      show evidence of minimal transport. A large mammalian assemblage has been
      collected from the deposits, showing a striking dominance of Alcelaphini
      […] to indicate the presence of extensive dry grasslands at KGA10’ (Suwa
      cs 1997).
      §
      Chesowanja A.boisei: ‘The fossiliferous sediments were deposited in a
      lagoon […] Abundant root casts […] suggest that the embayment was flanked
      by reeds and the presence of calcareous algae indicates that the lagoon
      was warm and shallow. Bellamya and catfish are animals tolerant of
      relatively stagnant water, and such situation would also be suitable for
      turtles and crocodiles’ (Carney cs 1971).
      §
      Olduvai middle Bed I: A.boisei OH.5 as well as habilis OH.7 and OH.62 were
      found in the most densely vegetated, wettest condition, with the highest
      lake levels (Walter cs 1991), near ostracods, freshwater snails, fish, and
      aquatic birds (Conroy, 1990); ‘[…] the middle Bed-I faunas indicate a very
      rich closed woodland environment, richer than any part of the present-day
      savanna biome in Africa […]’ (Fernández-Jalvo cs 1998). ‘Fossilized leaves
      and pollen are rare in the sediments of Beds I and II, but swamp
      vegetation is indicated by abundant vertical roots channels and casts
      possibly made by some kind of reed.
      Fossil rhizomes of papyrus also suggest the presence of marshland and/or
      shallow water’ (Conroy 1990). ‘[…] Cyperaceae fruits were common in H.
      habilis habitat (Bonnefille 1984). Ancient Egyptians ate Cyperus papyrus
      root which was also present at Olduvai in swamp-margins and river banks’
      (Puech 1992).






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