The origins of mammal growth patterns during the Jurassic mammalian radiation

We use synchrotron X-ray tomography of annual growth increments in the dental cementum of mammaliaforms (stem and crown fossil mammals) from three faunas across the Jurassic to map the origin of patterns of determinate growth, which is intrinsically related to mammalian endothermy. Although all fossils studied exhibited slower growth rates, longer lifespans, and delayed sexual maturity relative to comparably sized extant mammals, the earliest crown mammals developed significantly faster growth rates in early life that reduced at sexual maturity (determinate growth), compared to stem mammaliaforms. Estimation of basal metabolic rates (BMRs) suggests some fossil crown mammals had BMRs approaching the lowest rates of extant mammals. We suggest mammalian determinate growth first evolved during their mid-Jurassic adaptive radiation, although growth remained slower than in extant mammals., , , # The origins of mammal growth patterns during the Jurassic mammalian radiation

[https://doi.org/10.5061/dryad.b2rbnzsp2](https://doi.org/10.5061/dryad.b2rbnzsp2)

## Description of the data and file structure

This archive contains example data for X-ray tomographic scans of fossilised cementum from Mesozoic mammaliaform taxa studied for this research project, which was collected during several tomographic experiments at synchrotron X-ray sources.

Each folder contains Three subfolders representing the preservational category.

* Category A comprises the best-preserved specimens.
* Category B comprises specimens of less preservational quality than Category A but was still used in analyses.
* Category C comprises specimens deemed of too low preservational quality to use in analyses.

Each subfolder contains a PDF document for each specimen, comprising:

1. an example of a tomographic slice of the tooth root of the respective fossil specimen.
2. an image highlighting the region selected...