Exploring rates of change and modes of evolution in blastozoan echinoderms

Over the past half-century, paleobiologists have advanced the estimation of phylogenetic relationships among fossil taxa to explore evolutionary patterns in deep time. This study employs phylogenetics, divergence time calculations, and character rate evolution within three blastozoan echinoderm clades: Diploporita, Eublastoidea, and Paracrinoidea. Utilizing Reversible Jump Markov Chain Monte Carlo (rjMCMC) and Fossilized Birth-Death (FBD) models, we investigated evolutionary rates through anatomical subunit partitioning. Results suggest similar rates among the three groups, though Paracrinoidea exhibits elevated rates in several anatomical subunits. The inferred trees largely agree with other recently published analyses and highlight the need to revise echinoderm taxonomy. We tested different clock models for each group and found that model choice had strong effects on resulting trees; our findings suggest that linked clocks had more support than unlinked clocks. These findings indicate..., Recent work suggests variation in rates of evolution of echinoderm traits (Novack-Gottshall et al. 2022). In prior work, it has been hypothesized that “functional” traits like feeding characters may evolve at faster rates than other traits, a hypothesis not limited to echinoderms (e.g., Foote 1995; Ciampaglio 2002; Smith and Hopkins 2015; Wright 2017), but seen in animals in general (Wagner 1995; Sánchez-Villagra and Williams 1998). The morphological diversity seen in blastozoan echinoderms has frequently hindered our abilities to establish homology amongst characters, let alone examine rates of evolution. However, with the development of echinoderm-specific homology schemes (Mooi and David 1997; Sumrall 2010) and the application of these schemes to many blastozoan groups, these questions of evolution questions can be addressed. Both homology schemes have strengths and weaknesses (Sumrall et al. 2023), but, because this particular study is focused on Paleozoic blastozoans, and the mode..., , # Data from: Exploring rates of change and modes of evolution in blastozoan echinoderms

[https://doi.org/10.5061/dryad.s7h44j1hg](https://doi.org/10.5061/dryad.s7h44j1hg)

## Description of the data and file structure

Models of Character Evolution

A core goal in this study is to examine if the reversible jump Markov Chain Monte Carlo (rjMCMC) algorithm can be used to efficiently compare different hypotheses about character evolution. Reversible Jump Markov Chain Monte Carlo (rjMCMC) is an adaptation of the MCMC algorithm that allows for the number of parameters to change throughout an analysis. In this type of analysis, the model itself is a random variable. For example, in Table S1, you will note that some skyline models have more categories than others. In the case of adding a category, this means (minimally) adding three additional parameters — a new speciation, extinction, and fossil sampling rate. In a traditional MCMC, the number of parameters cannot be varied in an analysis. T...,