An early, non-calcified, dasycladalean alga from the Lower Devonian of Yunnan Province, China
Abstract
New data on the morphology of Uncatoella verticillata from the Lower Devonian Xiaxishancun Formation (Yunnan Province, China) demonstrate an affinity with Dasycladales rather than Charophyta as previously thought. The thallus is non-calcified and comprises a main axis with much branched, simple (acrophore) laterals in whorls (euspondyl). Occasional pseudodichotomies of the main axis are a unique feature of the species. Solitary, spherical, choristospore gametangiophores are borne laterally on first order lateral branches. Each choristospore contains a cluster of operculate cysts. These new data suggest an affinity with Dasycladaceae (sensu Berger and Kaever), and Uncatoella resembles most closely the weakly calcified living species in the tribes Bornetelleae and Batophoreae. Uncatoella possesses a suite of features usually associated with late Mesozoic and Cenozoic Dasycladales, and our proposed relationships imply very large range extensions (200-350 Myr) to some groups. These extended stratigraphic ranges probably reflect the absence of heavily mineralized forms early in the geological history of certain clades. Because the extent of biomineralization in Dasycladales is closely related to cell body architecture, we suggest that there is a representational bias in the group which favours certain morphotypes (densely branched, cortex forming) and which can lead to gross underestimation of stratigraphic ranges and historical diversity.
- Publication:
-
Review of Palaeobotany and Palynology
- Pub Date:
- 1998
- DOI:
- 10.1016/S0034-6667(97)00050-X
- Bibcode:
- 1998RPaPa.100...73K
- Keywords:
-
- Dasycladales;
- calcareous algae;
- Devonian;
- China;
- biomineralization