Modern Distribution Province *

S3. Latitudinal interval of the average position of the three selected limits of tropical climatic conditions through the Cenozoic in Europe and Africa north of the equator.

Age (Ma) * / Latitudinal position of the W Palearctic northern limit of the regions with MAP > 1000 mm/y on average (° N) / Latitudinal position of the W Palearctic southern limit of the regions with MAP > 1000 mm/y on average (° N) / Latitudinal position of the Afrotropical northern limit of the regions with MAP > 1000 mm/y on average (° N) / Latitudinal position of the northern limit of the regions with WMM > 20 °C on average (° N) / Latitudinal position of the northern limit of the regions with CMM > 10 °C on average (° N)
60 ‡ / > ca 60 † / > ca 60 †
58-57 § / <75 / <75
55-50 / >52 † / >52 †
50-45 / >53 † / >53 † / >50 †
45 / † / <80 / <80
40-35.5 / >53 † / >53 † / >53 †
34-31.5 / >53 † / >53 † / >47 †
31-28.5 / >47 † / >53 † / <47
26-24.5 / >47 † / >53 † / <47
24-23 / >47 † / >53 † / > ca 47 and < ca 53
22 / >53 † / >53 † / <47
21 / >49 † / >53 † / <47
19.5-17 / >53 † / >53 † / <47
17-15 / >45 † / >53 † / > ca 47 and < ca 53
14.5-13.5 / >53 † / >53 † / > ca 47 and < ca 53
13-12 / >53 † / ║ / ║ / >53 † / <47
12-10 / >53 † / <41 ** / ** / >53 † / >30 and <47
9-6 / >53 † / <41 / >53 † / >37.5 and <41
6-5.3 / † / <43 / †† / >51 † / >41 and <43
5.3-5 / † / >39.6 and <41.5 / †† / >53 † / >41 and <43
5-3.5 / † / >43 and <47 / ‡‡ / >51 † / <44
3.5-2 / † / >53 †
Pleistocene glacials (1.8-0.01) ††† / † / ca 40 / ca 7 §§ / ca 40 / >30 and <37
Holocene and Present (<0.01) ‡‡‡ / ca >60 and <68 / ca 40 / >10 and <15 *** / ca 45 / ca 40

At different times, the data from the table S2 were interpolated in order to provide these constraints on the latitudinal position of the limits of the tropical values for the three low atmosphere climatic parameters: WMM=20°C, CMM=10°C and MAP=1000 mm/yr.

*The periods are defined as short as possible, but wide enough to include data from localities providing sufficient constraint on latitudinal position of the climatic limits within these periods.

†The upper end of latitude intervals for WMM and CMM limits, and upper end for MAP limit in Europe, are not constrained by quantified data at these periods. However, they are materialised in the fig. S4 at purposedly high latitudes, and progressively joining the better constrained limits of adjacent periods. Hence these intervals are wide, but they almost certainly encompass the latitude of the corresponding limits.

‡Temperature limits indicated for this age in the fig. S4 are derived from tropical values of water paleo-temperatures. Water temperatures that equal or exceed tropical valuesin the North Sea Basin were found at 60.3 Ma [ref.1]: water WMM = 22.5 °C, water CMM = 16.9 °C (paleoproxy: deeper-dwelling sea water mollusc shells isotopes). Concordant interpretation derives from water temperatures in the Arctic (paleolatitude, ca 80 ° N) in the late Paleocene (Thanetian, ca 59-55 Ma) [ref. 2]: water minimal CMM = 9 °C, mean annual water temperature between 11 °C and 22 °C (closer to lower limit), mean annual range of water temperatures = ca 5-6 °C (consequently maximal water WMM = ca 15 °C or slightly higher) (paleoproxy: shallow marine coastal mollusc shells isotopes). This is also in accordance with mean annual air temperatures of 4 to 10 °C at a paleolatitude of 80 ° N in the early Paleocene [ref. 3].

§Temperature limits indicated for this age interval in the fig. S4 are derived from non-tropical values of water paleo-temperatures. Surface water temperatures well below tropical values were found at 75.3 ° N latitude on Ellesmere Island, at 58-57 Ma [ref. 4]: water WMM = 15.0 °C, water CMM = ca 5.0 °C(paleoproxy: coastal surface sea water mollusc shells isotopes).

║Indications of the onset of episodic arid climatic conditions in the region of the modern Sahara at ca 14 Ma [ref. 5]. Temporal interval limits marking the probable beginning and end of installation of more arid conditions at subtropical latitudes (ca 20 to 40 ° N) are based on the latter, and materialised by a hypothetical interval constraining the MAP limit between these latitudes. This MAP limit (fig. S4) is approximate.

**Emerging arid conditions in the Sahara region [ref. 6]. Earlier, humid tropical conditions generally existed in this region during the Eocene through the Miocene and locally the Pliocene [ref. 7].

††Indications of the possible emergence of a northern limit of humid tropical conditions in the afrotropical region, though not well defined [refs. 6-8].

‡‡Northern limit of humid tropical vegetation situated around 21 ° N in northwestern Africa between 3.7 and 3.5 Ma, and episodically later until 2.6 Ma [ref. 8].

§§Vegetation zones deduced from pollen data indicate a northern limit of humid tropical vegetation around 7 ° N at 18 000 yrs B.P. [ref. 9].

***Humid tropical MAP up to 27-29 ° N during Holocene optimum [ref. 10].

†††Parameters for glacial conditions in the Pleistocene are based on the quantified data for the LGM (Late Glacial Maximum, 18,000 y BP; seetable S2) and extrapolated to earlier Pleistocene glacials. The trends for the climate parameters in the Pleistocene are drawn (figs. S4, S5; Fig. 1) on the basis of these glacial conditions, because they dominated the period in terms of durations.

‡‡‡The data sources for the modern mean latitudes of climatic parameter limits are geographic atlases.

Estimates of the intervals for the different climatic limits average the data corresponding to different longitudes, in the geological record as well as for the modern data.

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2.Bice KL, Arthur MA, Marincovich Jr L (1996) Late Paleocene Arctic Ocean shallow-marine temperatures from mollusc stable isotopes. Paleoceanography 11: 241-249

3.Spicer RA, Parrish JT (1990) Late Cretaceous-early Tertiary palaeoclimates of northern high latitudes: a quantitative view. J Geol Soc Lond 147: 329-341

4.Tripati A, Zachos J, Marincovich Jr L, Bice K (2001) Late Paleocene Arctic coastal climate inferred from molluscan stable and radiogenic isotope ratios. Palaeogeogr Palaeoclim Palaeoecol 170: 101-113

5.Flower BP, Kennett JP (1994) The middle Miocene climatic transition: east Antarctic ice sheet development, deep ocean circulation and global carbon cycling. Palaeogeogr Palaeoclim Palaeoecol 108: 537-555

6.Griffin DL (2002) Aridity and humidity: two aspects of the late Miocene climate of North Africa and the Mediterranean. Palaeogeogr Palaeoclim Palaeoecol 182: 65-91

7.Le Houérou HN (1997) Climate, flora and fauna changes in the Sahara over the past 500 million years.J Arid Environ 37: 619-647

8.Leroy S, Dupont L (1994) Development of vegetation and continental aridity in northwestern Africa during the late Pliocene: the pollen record of ODP site 658. Palaeogeogr Palaeoclim Palaeoecol 109: 295-316

9.Elenga H, Peyron O, Bonnefille R, Jolly D, Cheddadi R, Guiot J, Andrieu V, Bottema S, Buchet G, de Beaulieu JL, Hamilton AC, Maley J, Marchant R, Perez-Obiol R, Reille M, Riollet G, Scott L, Straka H, Taylor D, Van Campo E, Vincens A, Laarif F, Jonson H (2000) Pollen-based biome reconstruction for southern Europe and Africa 18,000 yr BP. J Biogeogr 27: 621-634

10.Abed AM, Yaghan R (2000) On the paleoclimate of Jordan during the last glacial maximum. Palaeogeogr Palaeoclim Palaeoecol 160: 23-33