DOI: 10.5061/dryad.mt64k
title: Data from: Vascular patterns in the heads of crocodilians: blood vessels and sites of thermal exchange

description: Extant crocodilians are a highly apomorphic archosaur clade that is
 endothermic, yet often achieve large body sizes that can be subject to
 higher heat loads. Therefore, the anatomical and physiological roles that
 blood vessels play in crocodilian thermoregulation need further
 investigation to better understand how crocodilians establish and maintain
 cephalic temperatures and regulate neurosensory tissue temperatures during
 basking and normal activities. The cephalic vascular anatomy of extant
 crocodilians, particularly American alligator (Alligator mississippiensis)
 was investigated using a differential-contrast, dual-vascular injection
 technique and high resolution X-ray micro-computed tomography (μCT). Blood
 vessels were digitally isolated to create representations of vascular
 pathways. The specimens were then dissected to confirm CT results. Sites
 of thermal exchange, consisting of the oral, nasal, and orbital regions,
 were given special attention due to their role in evaporative cooling and
 cephalic thermoregulation in other diapsids. Blood vessels to and from
 sites of thermal exchange were studied to detect conserved vascular
 patterns and to assess their ability to deliver cooled blood to
 neurosensory tissues. Within the orbital region, both the arteries and
 veins demonstrated consistent branching patterns, with the supraorbital,
 infraorbital, and ophthalmotemporal vessels supplying and draining the
 orbit. The venous drainage of the orbital region showed connections to the
 dural sinuses via the orbital veins and cavernous sinus. The palatal
 region demonstrated a vast plexus that comprised both arteries and veins.
 The most direct route of venous drainage of the palatal plexus was through
 the palatomaxillary veins, essentially bypassing neurosensory tissues.
 Anastomotic connections with the nasal region, however, may provide an
 alternative route for palatal venous blood to reach neurosensory tissues.
 The nasal region in crocodilians is probably the most prominent site of
 thermal exchange, as it offers a substantial surface area and is
 completely surrounded by blood vessels. The venous drainage routes from
 the nasal region offer routes directly to the dural venous sinuses and the
 orbit, offering evidence of the potential to directly affect neurosensory
 tissue temperatures. The evolutionary history of crocodilians is complex,
 with large-bodied, terrestrial, and possibly endothermic taxa that may
 have had to deal with thermal loads that likely provided the anatomical
 building-blocks for such an extensive vascularization of sites of thermal
 exchange. A clear understanding of the physiological abilities and the
 role of blood vessels in the thermoregulation of crocodilians neurosensory
 tissues is not available but vascular anatomical patterns of crocodilian
 sites of thermal exchange indicate possible physiological abilities that
 may be more sophisticated than in other extant diapsids.
description: CT scan data of American
 alligator, Alligator mississippiensis (OUVC 9757)This zip file contains
 DICOM images from an x-ray microcomputed tomography (µCT) scan of an
 injected Alligator mississippiensis (OUVC 9757). The veins (with overflow
 into the arteries) were injected with a latex and barium solution and
 scanned on a GE eXplore Locus in vivo Small Animal MicroCT scanner (90µm
 slice thickness at 80kV and 450 µA) at the Ohio University µCT Scanning
 Facility.OhioU_WitmerLab_
 A_mississippiensis
 _OUVC_9757_venous-arterial_injection.zipCT scan data of American alligator, Alligator mississippiensis (OUVC 10387)This zip file contains DICOM images from an x-ray microcomputed tomography (µCT) scan of an injected Alligator mississippiensis (OUVC 10387). The veins were injected with a latex and barium solution and scanned on a GE eXplore Locus in vivo Small Animal MicroCT scanner (90µm slice thickness at 80kV and 450 µA) at the Ohio University µCT Scanning Facility.OhioU_WitmerLab_ A_mississippiensis _OUVC_10387_venous_injection.zipCT scan data of American alligator, Alligator mississippiensis (OUVC 10597)This zip file contains DICOM images from an x-ray microcomputed tomography (µCT) scan of an injected Alligator mississippiensis (OUVC 10597). The arteries and veins were injected with a latex and barium solution and scanned on a GE eXplore Locus in vivo Small Animal MicroCT scanner (90µm slice thickness at 80kV and 450 µA) at the Ohio University µCT Scanning Facility.OhioU_WitmerLab_ A_mississippiensis _OUVC_10597_DCDVI.zipCT scan data of a freshwater crocodile, Crocodylus johnstoni (OUVC 10426)This zip file contains DICOM images from an x-ray microcomputed tomography (µCT) scan of an injected Crocodylus johnstoni (OUVC 10426). The arteries and veins were injected with a latex and barium solution and scanned on a GE eXplore Locus in vivo Small Animal MicroCT scanner (90µm slice thickness at 80kV and 450 µA) at the Ohio University µCT Scanning Facility.OhioU_WitmerLab_ C_ johnstoni _OUVC_10426_DCDVI.zip3D-PDF of American alligator, Alligator mississippiensisPorter_Sedlmayr_Witmer_2016_Alligator_3D-PDF.pdf