Abstract
BackgroundAround the Cretaceous-Paleogene (K-Pg) boundary, an obvious global cooling occurred, which resulted in dramatic changes in terrestrial ecosystems and the evolutionary trends of numerous organisms. However, how plant lineages responded to the cooling has remained unknown until now. Between ca. 70–60 Ma Mesocyparis McIver & Basinger (Cupressaceae), an extinct conifer genus, was distributed from eastern Asia to western North America and provides an excellent opportunity to solve this riddle.ResultsHere we report a new species, Mesocyparis sinica from the early Paleocene of Jiayin, Heilongjiang, northeastern China. By integrating lines of evidence from phylogeny and comparative morphology of Mesocyparis, we found that during ca.70–60 Ma, the size of seed cone of Mesocyparis more than doubled, probably driven by the cooling during the K-Pg transition, which might be an effective adaptation for seed dispersal by animals. More importantly, we discovered that the northern limit of this genus, as well as those of two other arboreal taxa Metasequoia Miki ex Hu et Cheng (gymnosperm) and Nordenskioldia Heer (angiosperm), migrated ca.4–5° southward in paleolatitude during this time interval.ConclusionsOur results suggest that the cooling during the K-Pg transition may have been responsible for the increase in size of the seed cone of Mesocyparis and have driven the migration of plants southwards.
Highlights
Around the Cretaceous-Paleogene (K-Pg) boundary, an obvious global cooling occurred, which resulted in dramatic changes in terrestrial ecosystems and the evolutionary trends of numerous organisms
Metasequoia’s northern limit moved south by ca. 4 ° (Fig. 8 and Additional file 6: Table S5), while Nordenskioldia’s moved almost 5 ° (Fig. 8 and Additional file 7: Table S6). These findings indicate that the southward migration of the northern limit of Mesocyparis as driven by the cooling during the Cretaceous – Paleogene (K-Pg) transition is by no means unique
We report a new fossil species, Mesocyparis sinica from the early Paleocene of Jiayin, Heilongjiang, northeastern China
Summary
Around the Cretaceous-Paleogene (K-Pg) boundary, an obvious global cooling occurred, which resulted in dramatic changes in terrestrial ecosystems and the evolutionary trends of numerous organisms. 70–60 Ma Mesocyparis McIver & Basinger (Cupressaceae), an extinct conifer genus, was distributed from eastern Asia to western North America and provides an excellent opportunity to solve this riddle. 70–60 Ma), has been recorded by land plant leaf data [1] and marine oxygen isotope records [2]. These dramatic environmental and climate changes [3,4,5] altered the composition of terrestrial ecosystems and the evolutionary trends of numerous organisms. The extinct genus Mesocyparis McIver & Basinger (Cupressaceae) was distributed in eastern Asia and. The new Mesocyparis fossils from Northeast China, together with the other four species of this genus in the Northern Hemisphere, provide us with an opportunity to evaluate adaptions within the genus
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