Dead clades walking are a pervasive macroevolutionary pattern

Abstract

D. Jablonski [Proc. Natl. Acad. Sci. U.S.A. 99, 8139–8144 (2002)] coined the term “dead clades walking” (DCWs) to describe marine fossil orders that experience significant drops in genus richness during mass extinction events and never rediversify to previous levels. This phenomenon is generally interpreted as further evidence that the macroevolutionary consequences of mass extinctions can continue well past the formal boundary. It is unclear, however, exactly how long DCWs are expected to persist after extinction events and to what degree they impact broader trends in Phanerozoic biodiversity. Here we analyze the fossil occurrences of 134 skeletonized marine invertebrate orders in the Paleobiology Database (paleobiodb.org) using a Bayesian method to identify significant change points in genus richness. Our analysis identifies 70 orders that experience major diversity losses without recovery. Most of these taxa, however, do not fit the popular conception of DCWs as clades that narrowly survive a mass extinction event and linger for only a few stages before succumbing to extinction. The median postdrop duration of these DCW orders is long (>30 Myr), suggesting that previous studies may have underestimated the long-term taxonomic impact of mass extinction events. More importantly, many drops in diversity without recovery are not associated with mass extinction events and occur during background extinction stages. The prevalence of DCW orders throughout both mass and background extinction intervals and across phyla (>50% of all marine invertebrate orders) suggests that the DCW pattern is a major component of macroevolutionary turnover.

Transformative resonant moderation of geomagnetic polarity and strata

“…Instead, the record of evolution gets decimated together with, or within a short time from, topography-reshaping TREs. This reasoning agrees with the find that most species continue after an extinction event for more than 30 My, while many post-event drops in diversity without recovery are not associated with mass extinction events at all (Barnes et al, 2021). Similarly, pre-Milankovitch views that climate periodicity is due to changes in Earth's magnetic field (Puetz et al, 2016, Raup, 1985 made sense only due to the geomagnetism record's dominant bias in the same way.…”

“…The 10-My bin is a gauge best-fitting the overlap intervals, averaging the time for which most species continue after an extinction event (cf. Barnes et al, 2021, who found that most species continue for more than 30 My, while many drops in diversity without recovery are not associated with mass extinction events at all). Dashed arc depicts a period (wave) as it rolls out in the time domain.…”

Early evolution of beetles regulated by the end-Permian deforestation

“…Our results show that both the taxonomic diversity and morphological disparity dropped dramatically during the Early Triassic ( Figures 2 and 4 ). Combined with the phylogenetic results ( Figure 3 ), our suite of analyses yields a clear ecological signal from beetles across the Permian/Triassic boundary: all xylophagous stem-group beetles become extinct near the Permian-Triassic boundary or abruptly decreased in the Early Triassic (a pattern called ‘dead clade walking’; Barnes et al, 2021 ), while aquatic phoroschizid and ademosynid lineages crossed the Permian/Triassic boundary and diversified in the Middle Triassic. Coleoptera recovered in taxonomic diversity during the Middle Triassic by the rise of new predatory and herbivorous groups, synchronized with the recovery of terrestrial ecosystems ( Zhao et al, 2020 ).…”

Diversification dynamics of total-, stem-, and crown-groups are compatible with molecular clock estimates of divergence times

“…We do not investigate the effect of mass extinctions or varying rates of speciation and extinction which may better explain the timetree of life (12). If molecular clock estimates did exceed the expectations of this null model, an alternative model would have to be invoked to explain the findings [e.g., (29,30)]. However, the results of our simulations indicate that this is not currently necessary and that the molecular evidence and null expectations of tree shape are not in disagreement.…”