New record of Elatocladus from the Middle Jurassic of Iran, with global diversity and palaeogeography overview

Abstract

Newly discovered impression/compression conifer fossil specimens of Elatocladus are reported from the Middle Jurassic of the Tabas Block in Iran. The occurrence of buds at the base and apex and other characters of the specimens confirm that the present material can be attributed to Elatocladus laxus (Phillips) Harris 1979. This is the first record of E. laxus from Iran and one of the very few Laurasian occurrences of this taxon. Statistical data based on the palaeobotanical distribution of the genus Elatocladus from 337 localities (392 occurrences) suggest that this conifer had its main distribution in mid-to high-latitudinal (>30°N and >45°S) belts. The maximum relative frequency of this genus was restricted to palaeo-latitudes of 45°N to 60°N from the Middle Triassic up to the Late Cretaceous in Laurasia (62.6%) and palaeo-latitudes of 45°S to 60°S in Gondwana (69.31%). Across the Triassic/Jurassic Boundary (TJB), diversity of this genus decreases in the Northern Hemisphere and emigrates to high latitude belts. Therefore, it can be concluded that an event at low-latitudes and in Northern Hemisphere was the cause of this disappearance at the TJB, such as environmental and climatic disturbances related to the CAMP (Central Atlantic Magmatic Province). A statistical meta-analysis of the global distribution of Elatocladus records demonstrates that the genus was largely restricted to warm regions during the Mesozoic.