Neogene hyperaridity in Arabia drove the directions of mammalian dispersal between Africa and Eurasia

Abstract

The evolution of the present-day African savannah fauna has been substantially influenced by the dispersal of Eurasian ancestors into Africa. The ancestors evolved endemically, together with the autochthonous taxa, into extant Afrotropical clades during the last 5 million years. However, it is unclear why Eurasian ancestors moved into Africa. Here we use sedimentological observations and soluble salt geochemical analyses of samples from a sedimentary sequence in Western Iran to develop a 10-million-year long proxy record of Arabian climate. We identify transient periods of Arabian hyperaridity centred 8.75, 7.78, 7.50 and 6.25 million years ago, out-of-phase with Northern African aridity. We propose that this relationship promoted unidirectional mammalian dispersals into Africa. This was followed by a sustained hyperarid period between 5.6 and 3.3 million years ago which impeded dispersals and allowed African mammalian faunas to endemically diversify into present-day clades. After this, the mid-Piacenzian warmth enabled bi-directional fauna exchange between Africa and Eurasia, which continued during the Pleistocene.

Severe late Miocene droughts affected western Eurasia

“…Our combined data suggests a decoupling from the global system (Böhme et al, 2021), dominated by a local regional climate induced by tectonics and Paratethys volume and, more importantly, areal extent reduction.…”

“…Similarly high δ 13 CC29n-alkane values continue until 9.4 Ma, when in Western Europe increased seasonality accelerated the demise of the evergreen subtropical woodlands (Mosbrugger et al, 2005;Fortelius et al, 2014). The end of the Bessarabian (9.65 Ma) also corresponds to the maximum in dust mass accumulation rates typical of dry deposition announcing the onset of transient Arabian hyperaridity in the proximity of the Paratethys domain (Böhme et al, 2021). The other marked increased contribution of C4 plants and excessive drought observed in Panagia between 8.02 and 7.84 Ma appears to be correlated to a second period of Arabian hyperaridity centred at 7.78 Ma (Böhme et al, 2021).…”

“…The end of the Bessarabian (9.65 Ma) also corresponds to the maximum in dust mass accumulation rates typical of dry deposition announcing the onset of transient Arabian hyperaridity in the proximity of the Paratethys domain (Böhme et al, 2021). The other marked increased contribution of C4 plants and excessive drought observed in Panagia between 8.02 and 7.84 Ma appears to be correlated to a second period of Arabian hyperaridity centred at 7.78 Ma (Böhme et al, 2021). Using a 3D paleogeographic model Palcu et al (2021) calculated a ~ 70% loss of Paratethys surface and a ~33% volume reduction during regressions associated to the 9.66-9.28 and 8.02-7.84 Ma dry phases.…”

The exceptionally high diversity of small carnivorans from the Late Miocene hominid locality of Hammerschmiede (Bavaria, Germany)

“…Both localities have been characterized as typical Turolian (MN 12) faunas [ 38 ]. Significant faunal turnovers have taken place during the Aragonian-Vallesian and Vallesian-Turolian transitions [ 67 – 71 ] making the unaltered survival of a marten species (known for being rather speciose) seem highly improbable. Therefore, the comparison is mainly focused on the species “ M ”.…”

Biomarkers reveal two paramount Pliocene-Pleistocene connectivity events in the Caspian Sea Basin

“…A lake-level lowstand was initiated around 5.3 Ma and is marked by the deposition of a sequence of interbedded and regionally continuous lacustrine mudstones and fluvio-deltaic sandstones that form the main hydrocarbon reservoirs in the South Caspian region (Aliyeva, 2005;Kroonenberg et al, 2005;Vincent et al, 2010;Jorissen et al, 2019). The deposition of the Productive Series largely overlaps with the so-called Northern Arabian Desert Climax (5.59 and 3.3 Ma), when prolonged hyperaridity characterised the Arabian Peninsula (Böhme et al, 2021). Our δ 2 HC29n-alkanes support the idea of significantly drier conditions during the deposition of the lower part of the Lokbatan section.…”