DOI: 10.5061/dryad.fxpnvx12j
title: Supporting CT data for: Ontogenetic changes in endocranial anatomy in <em>Gorgosaurus libratus</em> (Theropoda: Tyrannosauridae) provide insight into the evolution of the tyrannosauroid endocranium

description: Over the past two decades, increased accessibility to computed tomographic
 (CT) scanners has allowed researchers to document the endocranium of
 numerous extinct theropod taxa. However, most of these studies have
 focused on the morphology of mature individuals. How endocranial
 morphology might vary through ontogeny in theropods remains largely
 unknown. Based on CT scans of braincases, we virtually reconstruct the
 endocranial morphology for a growth series of the
 tyrannosaurid Gorgosaurus libratus, including two recently
 discovered juvenile individuals, and compare it to that of other
 tyrannosauroids.  This study sheds light not only on the
 ontogenetic changes in endocranial anatomy in a tyrannosaurid but also on
 the variation in brain morphology among basal coelurosaurs. The endocasts
 of the smallest Gorgosaurus specimens (~50% adult skull length) exhibit
 more distinct cerebral hemispheres, optic lobes, and cerebella than do
 those of larger, more mature specimens. This suggests greater congruence
 between endocast-to-brain shape among juvenile tyrannosaurids and that
 their endocasts provide a more accurate representation of the brain than
 those of adult individuals. The brain morphology of Gorgosaurus is
 revealed to be intermediate between that of more basal sauropsids (e.g.,
 crocodilians) and derived coelurosaurs (e.g., birds). Plesiomorphic
 features include large olfactory bulbs and tracts, posteroventrally long
 axis of the cerebrum, and posterior position optic lobes, whereas derived
 features include a highly angular brain, somewhat enlarged cerebrum, and a
 cerebellum that at least partially separates the left and right optic
 lobes. Future research aiming to establish brain morphology in more basal
 theropods, such as tyrannosauroids, should consult endocasts of juvenile
 individuals, as these may more closely reflect the actual brain morphology
 and could better clarify the nature and timing of changes that led to the
 evolution of the avian brain.
description: # Ontogenetic changes in endocranial anatomy in *Gorgosaurus libratus*
 (Theropoda: Tyrannosauridae) provide insight into the evolution of the
 tyrannosauroid endocranium
 [https://doi.org/10.5061/dryad.fxpnvx12j](https://doi.org/10.5061/dryad.fxpnvx12j) #### Description of the data and file structure **Gorgosaurus_CT_Data.zip** **Summary** **TMP1991-36-500 (folder):** Folder containing CT data in DICOM and Amira mesh file formats and reconstructions of the endocast and endosseous labyrinths of the *Gorgosaurus* *libratus* specimen TMP 1991.036.0500. **TMP 1994-12-602 (folder)**: Folder containing CT data in DICOM and Amira mesh file formats and reconstructions of the endocast, endosseous labyrinths, cranial nerves, and braincase sinuses of the *Gorgosaurus* *libratus* specimen TMP 1994.012.0602. **TMP 2009-12-14 (folder)**: Folder containing CT data in DICOM and Amira mesh file formats and reconstructions of the endocast, endosseous labyrinths, and cranial nerves for the *Gorgosaurus* *libratus* specimen TMP 2009.012.0014. **TMP 2016-14-1 (folder)**: Folder containing CT data in DICOM and Amira mesh file formats and reconstructions of the endocast, endosseous labyrinths for the *Gorgosaurus* *libratus* specimen TMP 2016.014.0001. For additional correspondence or questions, email Jared Voris ([jared.voris@ucalgary.ca](mailto:jared.voris@ucalgary.ca)) **Descriptions** **Folder: TMP1991-36-500** Contains CT data and endocranial reconstructions of TMP 1991.036.0500. The specimen was CT scanned at Mayfair Diagnostics in Calgary, AB, Canada f, following the protocol of Ridgely and Witmer (2006: 120 kV, at between 200-300 mA, and with a slice thickness of 0.625 mm. The dataset was subsequently resampled to a voxel size of 0.3 x 0.3 x 0.3 mm. * DICOM(folder): CT data image series of 1176 individual scan images in DICOM format labelled “TMP 1991-36-500-Resampled.XXXX.dcm”. - TMP 1991-36-500-Resampled.am: CT data image series in Amira Mesh format * Endocast&endosseous.surf: Reconstruction of the endocast and endosseous labyrinth of TMP 1991.036.0500 in Amira Surface file format **Folder: TMP1994-12-602** Contains CT data and endocranial reconstructions of TMP 1994.012.0602. The specimen was CT scanned at the University of Calgary in Calgary, AB, Canada, following the protocol of Ridgely and Witmer (2006: 120 kV, at between 200-300 mA, and with a slice thickness of 0.625 mm. * DICOM(folder): CT data image series of 633 individual scan images in DICOM format labelled “TMP Gorgosaurus-braincase-TMP-94.12.602.XXXX.dcm”. - Gorgosaurus-braincase-TMP-94.12.602.am: CT data image series in Amira Mesh format * Basisphenoidal&Medial-Subcondylar-Recessi.surf: Reconstruction of the basisphenoid and medial subcondylar recesses of TMP 1994.012.0602 in Amira Surface file format - Caudal-Tympanic-Recess.surf: Reconstruction of the caudal tympanic recess of TMP 1994.012.0602 in Amira Surface file format * Cranial-nerves.surf: Reconstruction of the cranial nerves of TMP 1994.012.0602 in Amira Surface file format - Endocast surf: Reconstruction of the endocast of TMP 1994.012.0602 in Amira Surface file format * Endosseous-labyrinth.surf: Reconstruction of the endosseous labyrinths of TMP 1994.012.0602 in Amira Surface file format - Lateral-Subcondylar-Recess.sur f: Reconstruction of the lateral subcondylar recess of TMP 1994.012.0602 in Amira Surface file format * Rostral-Tympanic-Recess. surf: Reconstruction of the rostral tympanic recess of TMP 1994.012.0602 in Amira Surface file format - Subsellar-recess.surf: Reconstruction of the subsellar recess of TMP 1994.012.0602 in Amira Surface file format **Folder: TMP2009-12-14** Contains CT data and endocranial reconstructions of TMP 2009.012.0014. The specimen was CT scanned at the Drumheller Health Centre in Drumheller, AB, Canada, following the protocol of Ridgely and Witmer (2006: 120 kV, at between 200-300 mA), and with a slice thickness of 0.5 mm. The dataset was subsequently resampled to a voxel size of 0.3 x 0.3 x 0.3 mm. * DICOM(folder): CT data image series of 944 individual scan images in DICOM format labelled “GORGOSAURUS -2009.12.14.Resampled.XXXX.dcm”. - GORGOSAURUS -2009.12.14.Resampled.am: CT data image series in Amira Mesh format * TMP2009-12-14-Endocast&endosseous-Resampled.surf: Reconstruction of the endocast and endosseous labyrinth of TMP 2009.012.0014 in Amira Surface file format. - TMP2009-12-14-Endocast-Resampled3.obj: Reconstruction of the endocast and endosseous labyrinth of TMP 2009.012.0014 in obj file format. **Fol der:TMP2016-14-1** Contains CT data and endocranial reconstructions of TMP 2016.014.0001 “Blossom”. The specimen was CT scanned at the University of Calgary in Calgary, AB, Canada f, following the protocol of Ridgely and Witmer (2006: 120 kV, at between 200-300 mA), and with a slice thickness of 0.625 mm. The dataset was subsequently resampled to a voxel size of 0.3 x 0.3 x 0.3 mm. * DICOM(folder): CT data image series of 834 individual scan images in DICOM format labelled “BlossomTMP2016-14-1Resampled.XXXX.dcm”. - BlossomTMP2016-14-1Resampled.am: CT data image series in Amira Mesh format * TMP2016-14-1 Endocast&endosseous.surf: Reconstruction of the endocast and endosseous labyrinth of TMP 2016.014.0001 in Amira Surface file format.