DOI: 10.5061/dryad.vdncjsxrj
title: Data from: Cranial evolution in the extinct Rodrigues Island owl Otus murivorus (Strigidae), associated with unexpected ecological adaptations

description: Island birds that were victim of anthropic extinctions were often more
 specialist species, having evolved their most distinctive features in
 isolation. Here we studied a fossil cranium of the ‘giant’ extinct scops
 owl Otus murivorus from Rodrigues Island (Mascarene Islands, southwestern
 Indian Ocean), to determine any potential unique characters. The fossil
 and extant strigids were imaged through x-ray microtomography, providing
 3D views of external and internal (endocast, inner ear) cranial
 structures. Geometric morphometrics and analyses of traditional
 measurements yielded new information about the Rodrigues owl’s evolution
 and ecology. Otus murivorus exhibits a 2-tier “lag behind” phenomenon for
 cranium and brain evolution, both being proportionately small relative to
 increased body size. It also had a much more developed olfactory bulb than
 congeners, indicating an unexpectedly developed olfactory sense,
 suggesting a partial food scavenging habit. In addition, O. murivorus had
 the eyes placed more laterally than O. sunia, the species from which it
 was derived, probably a side effect of a small brain; rather terrestrial
 habits; probably relatively fearless behavior; and a less vertical posture
 (head less upright) than other owls (this in part an allometric effect of
 size increase). These evolutionary features, added to gigantism and wing
 reduction, make the extinct Rodrigues owl’s evolution remarkable, and with
 multiple causes.
description: This dataset comprises fossil cranium FLMR617 of the extinct owl
 <i>Otus murivorus</i> from Rodrigues Island, and ten crania of
 extant species of owls (Strigidae), as follows:
 <i>Otus scops </i>male (UCBL-FSL-SKT 246.2),
 <i>O. sunia </i>(MNHN-LAC 2000.329), <i>O. senegalensis
 </i>(MNHN-LAC 1997.476), <i>Megascops asio naevius
 </i>(UCBL-FSL-SKL 1856-540), <i>Bubo scandiacus </i>male
 (UCBL-FSL-SKL 2626), <i>B. bubo </i>male (UCBL-FSL-SKL, no
 number, from Ariège), <i>B. cinerascens </i>(UCBL-FSL-SKL 453,
 FSL), <i>B. zeylonensis </i>male (MNHN-LAC 1986-05),
 <i>At</i><i>hene noctua glaux </i>(UCBL-FSL-SKL
 568-379), <i>A</i><i>. cunicularia
 </i>(UCBL-FSL-SKL 656-436). Institutions
 abbreviations: FLMR, François Leguat Museum, Rodrigues, Republic of
 Mauritius; MNHN-LAC, Laboratoire d’Anatomie Comparée, collection of bird
 skeletons, Muséum National d’Histoire Naturelle, Paris, France;
 UCBL-FSL-SKL, collection de la Faculté des Sciences de Lyon de
 l’Université Claude Bernard Lyon 1 (Villeurbanne, France), category extant
 bird skulls; UCBL-FSL-SKT, collection de la Faculté des Sciences de Lyon
 de l’Université Claude Bernard Lyon 1 (Villeurbanne, France), category
 extant bird skeletons. All 11 specimens were imaged
 through x-ray microtomography at ENS de Lyon (GE Phoenix Nanotom 180
 device (platform US8/UMS3444 SFR BioSciences), in order to obtain 3D
 reconstructions of cranium, endocast and inner ear, as well as virtual
 sections of cranium. Details anout the parameters of all 11 scans are
 given with the data itself for every taxon (see Usage Notes).
description: For each of the 11 species, two files are compised here: (i) a
 .pca file (text file that comprises all the technical parameters of x-ray
 microtomography) ; (ii) a .raw file that is the scan volume. The .pca file
 names comprise the species name. The .raw file names comprise the species
 name, the number of slices in each of the 3 planes, the mention "8
 bit", and the voxel size at the initial stage of microtomography in
 micrometers (e.g., "45.8mic"). The 22 files are therefore as
 follows (in alphabetical order): Athene cunicularia:
 a_cunicularia_cranium_.pca ;
 A_cunicularia_840-621-1077-8bit-45.8mic.raw Athene
 noctua: A_noctua_cranium_.pca ;
 A_noctua_860-539-1050-8bit-48mic.raw Bubo bubo: B_bubo
 skull.pca ; B_bubo_1142-776-1122_8bit_64mic.raw Bubo
 cinerascens: B_cinerascens skull.pca ;
 B_cinerascens_966-701-1120_8bit_64mic.raw Bubo
 scandiacus: B_scandiacus skull.pca ;
 B_scandiacus_1142-848-1137_8bit_60mic.raw Bubo
 zeylonensis: B_zeylonensis skull.pca ;
 B_zeylonensis_1142-833-1127_8bit_64mic.raw Megascops
 asio: m_asio_cranium_.pca ; M_asio_834-633-1065_46mic.raw
 Otus murivorus: o_murivorus_cranium_.pca ;
 O_murivorus_1113-786-1050-8bit-36mic.raw Otus scops:
 o_scops_cranium_.pca ; O_scops_882-666-1067-8bit-36mic.raw
 Otus_senegalensis: O_senegalensis_cranium.pca ;
 O_senegalensis_840-685-1047-8bit-38mic.raw Otus_sunia:
 o_sunia_cranium_.pca ; O_sunia 831-636-1030_8bit_40mic.raw