title: The geological, isotopic, botanical, invertebrate, and lower vertebrate surroundings of Ardipithecus ramidus.
abstract: Sediments containing Ardipithecus ramidus were deposited 4.4 million years ago on an alluvial floodplain in Ethiopia's western Afar rift. The Lower Aramis Member hominid-bearing unit, now exposed across a > 9-kilometer structural arc, is sandwiched between two volcanic tuffs that have nearly identical 40Ar/39Ar ages. Geological data presented here, along with floral, invertebrate, and vertebrate paleontological and taphonomic evidence associated with the hominids, suggest that they occupied a wooded biotope over the western three-fourths of the paleotransect. Phytoliths and oxygen and carbon stable isotopes of pedogenic carbonates provide evidence of humid cool woodlands with a grassy substrate.
authors.affiliation: Earth Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA. wgiday@lanl.gov
authors.forename: Giday
authors.initials: G
authors.lastname: WoldeGabriel
authors.forename: Stanley H
authors.initials: SH
authors.lastname: Ambrose
authors.forename: Doris
authors.initials: D
authors.lastname: Barboni
authors.forename: Raymonde
authors.initials: R
authors.lastname: Bonnefille
authors.forename: Laurent
authors.initials: L
authors.lastname: Bremond
authors.forename: Brian
authors.initials: B
authors.lastname: Currie
authors.forename: David
authors.initials: D
authors.lastname: DeGusta
authors.forename: William K
authors.initials: WK
authors.lastname: Hart
authors.forename: Alison M
authors.initials: AM
authors.lastname: Murray
authors.forename: Paul R
authors.initials: PR
authors.lastname: Renne
authors.forename: M C
authors.initials: MC
authors.lastname: Jolly-Saad
authors.forename: Kathlyn M
authors.initials: KM
authors.lastname: Stewart
authors.forename: Tim D
authors.initials: TD
authors.lastname: White
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000032:analysis; D002254:Carbonates / Q000032:analysis; D017753:Ecosystem; D004777:Environment; D005002:Ethiopia; D035264:Flowers; D005580:Fossils; D019015:Geologic Sediments / Q000737:chemistry; D055593:Geological Phenomena; D015186:Hominidae; D007448:Invertebrates; D010103:Oxygen Isotopes / Q000032:analysis; D010944:Plants; D013696:Temperature; D014197:Trees; D014714:Vertebrates
chemical_list: D002247:Carbon Isotopes; D002254:Carbonates; D010103:Oxygen Isotopes