Data from: From success to persistence: Identifying an evolutionary regime shift in the diverse Paleozoic aquatic arthropod group Eurypterida, driven by the Devonian biotic crisis

Mass extinctions have altered the trajectory of evolution a number of
times over the Phanerozoic. During these periods of biotic upheaval a
different selective regime appears to operate, although it is still
unclear whether consistent survivorship rules apply across different
extinction events. We compare variations in diversity and disparity across
the evolutionary history of a major Paleozoic arthropod group, the
Eurypterida. Using these data, we explore the group's transition from
a successful, dynamic clade to a stagnant persistent lineage, pinpointing
the Devonian as the period during which this evolutionary regime shift
occurred. The late Devonian biotic crisis is potentially unique among the
‘Big Five’ mass extinctions in exhibiting a drop in speciation rates
rather than an increase in extinction. Our study reveals eurypterids show
depressed speciation rates throughout the Devonian but no abnormal peaks
in extinction. Loss of morphospace occupation is random across all
Paleozoic extinction events; however, differential origination during the
Devonian results in a migration and subsequent stagnation of occupied
morphospace. This shift appears linked to an ecological transition from
euryhaline taxa to freshwater species with low morphological diversity
alongside a decrease in endemism. These results demonstrate the importance
of the Devonian biotic crisis in reshaping Paleozoic ecosystems.