DOI: 10.5061/dryad.w3r2280rh
title: Effect of captivity on the vertebral bone microstructure of Xenarthran mammals

description: Captive specimens in museum collections facilitate study of rare taxa, but
 the lifestyles, diets, and lifespans of captive animals differ from their
 wild counter- parts. Trabecular bone architecture adapts to in vivo
 forces, and may reflect interspecific variation in ecology and behavior as
 well as intraspecific variation between captive and wild specimens. We
 compared trunk vertebrae bone microstructure in captive and wild
 xenarthran mammals to test the effects of ecology and captivity. We
 collected μCT scans of the last six presacral vertebrae in 13
 fossorial, terrestrial, and suspensorial xenarthran species (body mass:
 120 g to 35 kg). For each vertebra, we measured centrum length; bone
 volume fraction (BV.TV); trabecular number and mean thickness (Tb.Th);
 global com- pactness (GC); cross-sectional area; mean intercept length;
 star length distribu- tion; and connectivity and connectivity density.
 Wild specimens have more robust trabeculae, but this varies with species,
 ecology, and pathology. Wild specimens of fossorial taxa (Dasypus) have
 more robust trabeculae than cap- tives, but there is no clear difference
 in bone microstructure between wild and captive specimens of suspensorial
 taxa (Bradypus, Choloepus), suggesting that locomotor ecology
 influences the degree to which captivity affects bone micro- structure.
 Captive Tamandua and Myrmecophaga have
 higher BV.TV, Tb.Th, and GC than their wild counterparts due to
 captivity-caused bone pathologies. Our results add to the understanding of
 variation in mammalian bone micro- structure, suggest caution when
 including captive specimens in bone micro- structure research, and
 indicate the need to better replicate the habitats, diets, and behavior of
 animals in captivity.
description: We chose 44 adult xenarthran specimens from the FMNH Mammalogy
 collections to undergo X-ray micro-computed tomography (μCT) scanning at
 the University of Chicago’s PaleoCT facility
 (https://luo-lab.uchicago.edu/paleoCT.html). We scanned the last six
 presacral vertebrae of each specimen. We scanned all specimens using the
 240 kV tube of the PaleoCT lab’s GE v|tome|x μCT scanner at resolutions
 from 22.101 µm to 96.551 µm (average resolution 44.899 µm), depending on
 specimen size. We reconstructed the scans in GE phoenix datos|x and
 aligned and cropped the reconstructed scans using VGstudio (Volume
 Graphics, 2019). We segmented prism-shaped volumes of interest (VOI) from
 the vertebral centra. We determined the size and location of the prism by
 orienting the vertebra in cranial view and selecting the largest 2D square
 area of trabecular bone at the dorsoventrally and mediolaterally narrowest
 point of the centrum. Using the “Threshold” tool in FIJI, we converted the
 VOI into a binary image stack in which we maximized bone sampling and
 minimized sampling of non-bone materials. We additionally segmented out
 entire vertebrae including only the slices where the vertebral foramen was
 completely surrounded by bone and binarized them using the same threshold
 as the VOI. 
description: Readme file is uploaded.  Specimen
 list:     FMNH 18835     Tamandua mexicana<br>   
  FMNH 25271     Priodontes maximus<br>     FMNH 26563   
  Myrmecophaga tridactyla<br>     FMNH 28309     Myrmecophaga
 tridactyla<br>     FMNH 28342     Tolypeutes matacus<br>   
  FMNH 39307     Dasypus novemcinctus<br>     FMNH 39468   
  Chlamyphorus truncatus<br>     FMNH 51889     Cyclopes
 didactylus<br>     FMNH 58802     Cyclopes didactylus<br>   
  FMNH 60082     Dasypus novemcinctus<br>     FMNH 60164     Bradypus
 variegatus<br>     FMNH 60455     Choloepus hoffmanni<br>   
  FMNH 60468     Dasypus novemcinctus<br>     FMNH 60493     Dasypus
 novemcinctus<br>     FMNH 60547     Tamandua tetradactyla<br>
     FMNH 60688     Myrmecophaga tridactyla<br>     FMNH 61854   
  Cyclopes didactylus<br>     FMNH 68919     Bradypus
 variegatus<br>     FMNH 69576     Choloepus didactylus<br>   
  FMNH 69587     Bradypus variegatus<br>     FMNH 69589     Bradypus
 variegatus<br>     FMNH 69971     Cyclopes didactylus<br>   
  FMNH 72913     Priodontes maximus<br>     FMNH 74246   
  Chlamyphorus truncatus<br>     FMNH 93296     Bradypus
 didactylus<br>     FMNH 95448     Choloepus didactylus<br>   
  FMNH 104817     Zaedyus Pichiy<br>     FMNH 104986     Chlamyphorus
 truncatus<br>     FMNH 105031     Chlamyphorus truncatus<br>
     FMNH 121192     Tamandua mexicana<br>     FMNH 121540   
  Tolypeutes matacus<br>     FMNH 121653    Cyclopes
 didactylus<br>     FMNH 123994     Tamandua mexicana<br>   
  FMNH 124570    Tolypeutes matacus<br>     FMNH 134417    Dasypus
 novemcinctus<br>     FMNH 137419    Tamandua tetradactyla<br>
     FMNH 140358    Cyclopes didactylus<br>     FMNH 140912  
  Tamandua mexicana<br>     FMNH 153782    Zaedyus pichiy<br>
     FMNH 156654    Cyclopes didactylus<br>     FMNH 159987  
  Myrmecophaga tridactyla<br>     FMNH 165373    Choloepus
 hoffmanni<br>     FMNH 165374    Choloepus hoffmanni<br>   
  FMNH 186913    Tamandua tetradactyla