Helicoconchus elongatus, a microconchid from the Lueders Formation of Texas.
Description
Paleogeography
At the time of deposition, a broad sea connected to the
Panthalassic Ocean covered much of the central United States, including Texas. The Lueders Formation would have been located in the
northern tropics or
subtropics. Climatically, after the retreat of an early
Artinskianglacial maximum, the deserts of the
North American craton experienced fluctuation and growth during this time period, and the associated aridity decrease impacted seabed deposition in localities across the basin.[2]
Depositional environment
The Lueders Formation represents a
deltaic environment, with terrestrial sediments being deposited onto the muddy bottom of a shallow
estuary by shifting freshwater streams. In the Maybelle Member, the
dolomite likely represents
marine deposits, preserving marine sharks and fish, whereas darker terrestrial sediments and freshwater
shale deposits contain remains of land animals and freshwater fish respectively.[3]
^
abcJohnson, G. D. (1999). "Dentitions of Late Palaeozoic Orthacanthus species and new species of ?Xenacanthus (Chondrichthyes: Xenacanthiformes) from North America". Acta Geologica Polonica.
S2CID128796206.