Re: Proven facts (Re: Savanna hunters run down kudus (Re: AAT all washed up(WARNING: graphic photo)
- From: Marc Verhaegen <m_verhaegen@xxxxxxxxx>
- Date: Fri, 03 Aug 2007 02:59:43 +0200
Op 03-08-2007 01:07, in artikel
1186096077.344188.80970@xxxxxxxxxxxxxxxxxxxxxxxxxxx, nickname
<alas_my_loves@xxxxxxxxx> schreef:
Marc Verhaegen, Pierre-François Puech and
Stephen Munro
Aquarboreal ancestors?
TRENDS in Ecology & Evolution Vol.17 No.5 May 2002
Australopithecine lifestyle
The list shows that some very early hominids, more than later
australopithecines, have been found near lacustrine molluscs (Lukeino and
Tabarin ca. 6.5 and 5 Myr BP). Ardipithecus ramidus, supposedly another
early hominid, must have lived in a wooded habitat, amid predominantly
colobine monkeys (Aramis ca. 4.5 Myr BP). Pliocene australopithecines ca.
4-3 Myr BP apparently frequently dwelt in warm and humid, more or less
closed environments (gallery forest or wooded habitat in Kanapoi, Chad,
Hadar, Makapansgat, but inconclusive for Garusi-Laetoli). Pleistocene robust
australopithecines since 2.5 Myr BP probably lived in generally dryer and
more open landscapes (grassland in Kromdraai and Konso), but their remains
lay in riverbanks, lagoons, marshes, lake-margins, near papyrus (Olduvai)
and reed (Kromdraai, Olduvai, Chesowanja).
Although ?all nine Konso A. boisei specimens were recovered among the
predominantly dry grassland fauna of KGA 10¹ (Suwa et al., 1997), this does
not mean that they lived in a savanna milieu, since ?nearby subsites were
also moist and wooded¹ (Delson, 1997). Fragmentary fossils like those of
Laetoli and Konso are often the remains of carnivore meals (Morden, 1988).
Leopards, which preyed upon australopithecines, prefer to feed in dry
circumstances and therefore drag away their prey, sometimes several hundred
meters (Brain, 1981).
The preponderance of wet environments in our list is striking, but this was
not considered to be inconsistent with a savanna view, because it was
believed that the fossil record sampled a disproportionate number of
habitats related to water (see the above citation from Shipman and Harris,
1988). To be sure, that the hominids have been discovered in humid or wet
habitats does not allow firm conclusions about how much time they spent
there, but the possibility that wetter rather than drier conditions
influenced hominid evolution can not be ignored. Therefore, paleo-ecological
data must be verified and supplemented through anatomical and especially
dental studies of the fossils.
It is generally agreed that all australopithecines have skeletal features of
bipedality. Early graciles also show clear indications of tree climbing such
as curved manual and pedal phalanges, though such features are less obvious
in the robusts.
Dental studies suggest that whereas gracile australopithecines preferred
softer fruits and vegetables, the robusts¹ diet included harder food items
(e.g. Robinson, 1954; Du Brul, 1977; Walker, 1981; Puech, 1992; Lee-Thorp et
al., 1994). Estimates of robust australopithecine bite force suggest
?low-energy food that had to be processed in great quantities¹ and food
objects ?hard and round in shape¹ (Demes & Creel, 1988). Du Brul (1977)
noticed dental isms between the robust australopithecines and the
bamboo-eating giant panda Ailuropoda melanoleuca (broad, high and heavy
cheekbones, reduced prognathism and front teeth, broad back teeth, premolar
molarisation), as opposed to gracile australopithecines, respectively
non-panda bears.
Papyrus and reed were present in the paleo-environment of the later
australopithecines (e.g. Olduvai, Chesowanja, Kromdraai), and Cyperaceae and
Gramineae are part of the diet of living African hominoids. Gorillas eat
sedges and bamboo shoots and stalks, gorillas and chimpanzees eat cane,
chimps and humans eat water lilies, and rice and other cereals are staple
food for humans. Supplementing their diet with parts of grasslike plants
might have been enabled the robusts to bridge the dry season, when fruits
and soft vegetables were scarce.
Studies of dental enamel microwear provide other details. In the early
australopithecines of Garusi-Laetoli and Hadar (A. afarensis 4-3 Myr BP),
the cheekteeth enamel has a polished surface and the microwear looks like
that of the capybara Hydrochoerus hydrochaeris and that of the mountain
beaver Aplodontia rufa (Puech et al., 1986). These animals are semi-aquatic
rodents that feed mainly on sappy marsh and
mountain beavers prefer to den near streams IIRC. Dunno if they avoid
water, but I don't think so.
Well, there is some savanna maniac that believes that because we wrote in
our TREE paper that mountain beavers are semi-aquatic, that this would
contradict that capibaras, mountain beaves & afarensis (all 3 have glossy
appearance of molar enamel, due to polishing by succulent plants, see Puech)
ate succulent plants... If they have nothing better... Sad, sad...
--Marc
.
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