Polymorphic organization in a planktonic graptoloid (Hemichordata: Pterobranchia) colony of Late Ordovician age

Graptoloid diversity and disparity became decoupled during the Ordovician mass extinction.

The morphological study of extinct taxa allows for analysis of a diverse set of macroevolutionary hypotheses, including testing for change in the magnitude of morphological divergence, extinction selectivity on form, and the ecological context of radiations. Late Ordovician graptoloids experienced a phylogenetic bottleneck at the Hirnantian mass extinction (∼445 Ma), when a major clade of grapt...

The first report of cryptospore assemblages of Late Ordovician in Iran, Ghelli Formation, Eastern Alborz

For the first time, an assemblage of cryptospores, which includes 10 species belonging to nine genera, from the Upper Ordovicianstrata, is being reported, in Iran. These cryptospore assemblages were recovered from the upper part of Ghelli Formation., from theeastern Alborz Mountain range. These peri-Gondwanan cryptospores have been classified based on their morphology (monad, truedyad, pseudody...

The magnitude and duration of Late Ordovician-Early Silurian glaciation.

Understanding ancient climate changes is hampered by the inability to disentangle trends in ocean temperature from trends in continental ice volume. We used carbonate "clumped" isotope paleothermometry to constrain ocean temperatures, and thereby estimate ice volumes, through the Late Ordovician-Early Silurian glaciation. We find tropical ocean temperatures of 32° to 37°C except for short-lived...

Flexible colony-founding strategies in a socially polymorphic ant

The Global Diversity of Hemichordata.

Phylum Hemichordata, composed of worm-like Enteropneusta and colonial Pterobranchia, has been reported to only contain about 100 species. However, recent studies of hemichordate phylogeny and taxonomy suggest the species number has been largely underestimated. One issue is that species must be described by experts, and historically few taxonomists have studied this group of marine invertebrates...