TY - JOUR

T1 - Northward dispersal of dinosaurs from Gondwana to Greenland at the mid-Norian (215-212 Ma, Late Triassic) dip in atmospheric pCO(2)

AU - Kent, Dennis

AU - Clemmensen, Lars B.

PY - 2021

Y1 - 2021

N2 - The earliest dinosaurs (theropods and sauropodomorphs) are found in fossiliferous early Late Triassic strata dated to about 230 million years ago (Ma), mainly in northwestern Argentina and southern Brazil in the Southern Hemisphere temperate belt of what was Gondwana in Pangea. Sauropodomorphs, which are not known for the entire Triassic in then tropical North America, eventually appear 15 million years later in the Northern Hemisphere temperate belt of Laurasia. The Pangea supercontinent was traversable in principle by terrestrial vertebrates, so the main barrier to be surmounted for dispersal between hemispheres was likely to be climatic; in particular, the intense aridity of tropical desert belts and unstable climate in the equatorial humid belt accompanying high atmospheric pCO(2) that characterized the Late Triassic. We revisited the chronostratigraphy of the dinosaurbearing Fleming Fjord Group of central East Greenland and, with additional data, produced a correlation of a detailed magnetostratigraphy from more than 325 m of composite section from two field areas to the age-calibrated astrochronostratigraphic polarity time scale. This age model places the earliest occurrence of sauropodomorphs (Plateosaurus) in their northernmost range to similar to 214 Ma. The timing is within the 215 to 212 Ma (mid-Norian) window of a major, robust dip in atmospheric pCO(2) of uncertain origin but which may have resulted in sufficiently lowered climate barriers that facilitated the initial major dispersal of the herbivorous sauropodomorphs to the temperate belt of the Northern Hemisphere. Indications are that carnivorous theropods may have had dispersals that were less subject to the same climate constraints.

AB - The earliest dinosaurs (theropods and sauropodomorphs) are found in fossiliferous early Late Triassic strata dated to about 230 million years ago (Ma), mainly in northwestern Argentina and southern Brazil in the Southern Hemisphere temperate belt of what was Gondwana in Pangea. Sauropodomorphs, which are not known for the entire Triassic in then tropical North America, eventually appear 15 million years later in the Northern Hemisphere temperate belt of Laurasia. The Pangea supercontinent was traversable in principle by terrestrial vertebrates, so the main barrier to be surmounted for dispersal between hemispheres was likely to be climatic; in particular, the intense aridity of tropical desert belts and unstable climate in the equatorial humid belt accompanying high atmospheric pCO(2) that characterized the Late Triassic. We revisited the chronostratigraphy of the dinosaurbearing Fleming Fjord Group of central East Greenland and, with additional data, produced a correlation of a detailed magnetostratigraphy from more than 325 m of composite section from two field areas to the age-calibrated astrochronostratigraphic polarity time scale. This age model places the earliest occurrence of sauropodomorphs (Plateosaurus) in their northernmost range to similar to 214 Ma. The timing is within the 215 to 212 Ma (mid-Norian) window of a major, robust dip in atmospheric pCO(2) of uncertain origin but which may have resulted in sufficiently lowered climate barriers that facilitated the initial major dispersal of the herbivorous sauropodomorphs to the temperate belt of the Northern Hemisphere. Indications are that carnivorous theropods may have had dispersals that were less subject to the same climate constraints.

KW - magnetostratigraphy

KW - Triassic

KW - dinosaurs

KW - Pangea

KW - paleoclimate

KW - FOREST NATIONAL-PARK

KW - CENTRAL EAST GREENLAND

KW - LOS COLORADO FORMATION

KW - KAP STEWART FORMATION

KW - JAMESON LAND BASIN

KW - EARLY EVOLUTION

KW - CHINLE FORMATION

KW - FLEMING FJORD

KW - AGE CONSTRAINTS

KW - STRATIGRAPHY

U2 - 10.1073/pnas.2020778118

DO - 10.1073/pnas.2020778118

M3 - Journal article

C2 - 33593914

VL - 118

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 8

M1 - 2020778118

ER -