New record of conifer wood Agathoxylon from the Upper Jurassic in the Sichuan Basin, southern China, and its palaeobiodiversity and palaeoclimatic significance

ABSTRACT

Although abundant and diverse foliage fossils are well recorded in the Upper Triassic and Lower–Middle Jurassic of the Sichuan Basin in South China, the Upper Jurassic plant fossils are rarely documented due to extensively developed red beds in this basin. Decades ago, abundant fossil wood specimens were discovered from the Upper Jurassic Penglaizhen Formation in the Sichuan Basin. However, detailed investigations on the systematic palaeobotany of these wood fossils are very limited, which hinders further understanding of the terrestrial ecosystem and biota. Here, we describe anatomically well-preserved fossil wood specimens from the Penglaizhen Formation at Wangjiagou Village of Shehong City in the central Sichuan Province. These wood fossils exhibit Agathoxylon anatomy with usually uniseriate contiguous radial tracheid pitting and araucarioid cross-field pitting, representing a new record of Agathoxylon in the Sichuan Basin, and contribute to further understanding of the vegetation composition of the southern phytoprovince in China during the Late Jurassic. Independent palaeoclimatic evidence from leaf, pollen and sediments indicates that the Agathoxylon trees from Shehong area have grown under generally hot and semi-arid or arid environmental conditions, probably in habitats at the banks of rivers and lakes with locally abundant water supply, as indicated by the indistinct growth rings.

KEYWORDS:

• Agathoxylon
• Kimmeridgian–Tithonian
• Palaeoclimate
• Shehong

Acknowledgments

We thank Li Zhang at NIGPAS for helpful discussion, as well as other colleagues in NIGPAS, Dazhou, Chengdu and Shehong for their field assistance. This work was co-sponsored by the National Natural Science Foundation of China (NSFC 42330208, 41790454, 41972007, 42002023), Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB26000000), the State Key Laboratory of Palaeobiology and Stratigraphy (20172103, 20191103, 20192101).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All the related data are described in the study.

Additional information

Funding

The work was supported by the National Natural Science Foundation of China Strategic Priority Research Program (B) of the Chinese Academy of Sciences State Key Laboratory of Palaeobiology and Stratigraphy.