DOI: 10.5061/dryad.27m63
title: Data from: Vascular patterns in iguanas and other squamates: blood vessels and sites of thermal exchange

description: Squamates use the circulatory system to regulate body and head
 temperatures during both heating and cooling. The flexibility of this
 system, which possibly exceeds that of endotherms, offers a number of
 physiological mechanisms to gain or retain heat (e.g., increase peripheral
 blood flow and heart rate, cooling the head to prolong basking time for
 the body) as well as to shed heat (modulate peripheral blood flow, expose
 sites of thermal exchange). Squamates also have the ability to establish
 and maintain the same head-to-body temperature differential that birds,
 crocodilians, and mammals demonstrate, but without a discrete rete or
 other vascular physiological device. Squamates offer important anatomical
 and phylogenetic evidence for the inference of the blood vessels of
 dinosaurs and other extinct archosaurs in that they shed light on the
 basal diapsid condition. Given this basal positioning, squamates likewise
 inform and constrain the range of physiological thermoregulatory
 mechanisms that may have been found in Dinosauria. Unfortunately, the
 literature on squamate vascular anatomy is limited. Cephalic vascular
 anatomy of green iguanas (Iguana iguana) was investigated using a
 differential-contrast, dual-vascular injection (DCDVI) technique and
 high-resolution X-ray microcomputed tomography (μCT). Blood vessels were
 digitally segmented to create a surface representation of vascular
 pathways. Known sites of thermal exchange, consisting of the oral, nasal,
 and orbital regions, were given special attention due to their role in
 brain and cephalic thermoregulation. Blood vessels to and from sites of
 thermal exchange were investigated to detect conserved vascular patterns
 and to assess their ability to deliver cooled blood to the dural venous
 sinuses. Arteries within sites of thermal exchange were found to deliver
 blood directly and through collateral pathways. The venous drainage was
 found to have multiple pathways that could influence neurosensory tissue
 temperature, as well as pathways that would bypass neurosensory tissues.
 The orbital region houses a large venous sinus that receives cooled blood
 from the nasal region. Blood vessels from the nasal region and orbital
 sinus show anastomotic connections to the dural sinus system, allowing for
 the direct modulation of brain temperatures. The generality of the
 vascular patterns discovered in iguanas were assessed by firsthand
 comparison with other squamates taxa (e.g., via dissection and
 osteological study) as well as the literature. Similar to extant
 archosaurs, iguanas and other squamates have highly vascularized sites of
 thermal exchange that likely support physiological thermoregulation that
 “fine tunes” temperatures attained through behavioral thermoregulation.
description: CT scan data of green
 iguana, Iguana iguana OUVC 10445This zip file contains
 DICOM images from an x-ray microcomputed tomography (µCT) scan of an
 injected Iguana iguana (OUVC 10445). 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_Iguana_iguana_OUVC_10445_arterial_injection.zipCT scan data of green iguana, Iguana iguana OUVC 10603This zip file contains DICOM images from an x-ray microcomputed tomography (µCT) scan of an injected Iguana iguana (OUVC 10603). 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_Iguana_iguana_OUVC_10603_arterial_injection.zipCT scan data of green iguana, Iguana iguana OUVC 10611This zip file contains DICOM images from an x-ray microcomputed tomography (µCT) scan of an injected Iguana iguana (OUVC 10611). 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_Iguana_iguana_OUVC_10611_arterial_injection.zipCT scan data of green iguana, Iguana iguana OUVC 10612This zip file contains DICOM images from an x-ray microcomputed tomography (µCT) scan of an injected Iguana iguana (OUVC 10612). 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_Iguana_iguana_OUVC_10612_venous_injection.zipCT scan data of green iguana, Iguana iguana OUVC 10709This zip file contains DICOM images from an x-ray microcomputed tomography (µCT) scan of an injected Iguana iguana (OUVC 10709). 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_Iguana_iguana_OUVC_10709_arterial_injection.zip3D-PDF of green iguana, Iguana iguanaPorter&Witmer_2015_Iguana 3D-PDF.pdf