Orbital Margin Research Articles

Length of orbital margins of dry skulls in a local Pakistani population

Orbit is an important bony cavity which lodges eyeball and associated structures for our fundamental sense of vision. Knowledge regarding accurate morphometric measurements of its margins and depth will help in diagnosis and treatment plans of various optic functions. Previous studies showed racial differences in different populations we want to collect data in local population of Asian region as we are lacking data in this region. This study was carried out on 64 bony orbits of 32 dry Asian human skulls. Measurements from right and left bony orbits were taken by digital vernier calipers in millimeters and entered in SPSS 18.0 for calculation of mean and standard deviation.Results were obtained from different orbital margins. Right superior, inferior, medial and lateral orbital margins showed results as 31.30 ± 2.329 mm, 33.59 ± 3.35 mm, 29.57 ± 2.28 mm and 28.37 ± 2.023 mm respectively. While left superior, inferior, medial and lateral orbital margins were 30.944 ± 2.1080 mm, 31.19 ± 2.54 mm, 29.567 ± 2.36 mm and 28.14 ± 2.286 mm respectively. Right sided depth from optic canal to frontomaxillary suture was 41.40 ± 2.88 and left sided depth was 39.93 ± 3.33 mm. Data collected in Asian population showed differences from other races. This study covers important area regarding helpful in surgeries of this region as precise measurements could avoid injuries and postoperative complications.Key Words: Orbital Margin, Pakistan

P100 Removing the orbital bar in fronto-orbital advancement and reconstruction

ObjectivesTo describe our technique of using reverse frontal bone graft for FOAR for patients with metopic or coronal synostosis.DesignRetrospective analysis of digital records for operation notes and radiological images.SubjectsSince April 2014, 16 patients underwent FOAR without using orbital bar.MethodsWe plan a frontal bone graft using Marchac template and increase the angles on side by 1 cm. This graft is then reversed and supra orbital margins are drilled out. The orbital bar is then removed and drilled down to make bone dust which is then used to fill gaps on exposed dura. The reversed frontal graft is then placed in front and secured via absorbable sutures, plate and screws.ResultsAll 16 patients who underwent this technique have shown excellent cosmetic results with no complications or non healing. Removing orbital bar does not cause any cosmetic defect since orbital rims are drilled out in reverse frontal bone graft. The removed orbital bar provides an excellent source of bone dust to cover gaps on exposed dura.ConclusionsWe present our technique of FOAR without using orbital bar, which is drilled down to bone dust to fill gaps. This has shown excellent cosmetic results so far with no complications. This addresses the issue of temporal thinning.

Reliability and accuracy of skin-supported surgical templates for computer-planned craniofacial implant placement, a comparison between surgical templates: With and without bony fixation

IntroductionThe purpose is to determine the accuracy of guided implant placement in the orbital, nasal, and auricular region using computer-aided designed stereolithographic skin-supported surgical templates with and without bone fixation pins. Materials and MethodsPreoperatively, cone-beam CT (CBCT) and multiple detector computed tomography (MDCT) scans were acquired from 10 cadaver heads, followed by virtual planning of implants in the orbital margin, auricular region and nasal floor. Surgical skin-supported templates were digitally designed to allow flapless implant placement. Fixation pins were used for stabilization comprising half of all templates in predetermined bone areas. The accuracy of the surgical templates was validated by comparing the achieved implant location to its virtual planned implant position by calculating the linear and angular deviations. ResultsSurgical templates with the use of bone fixation pins produced statistically significant greater implant deviations as compared to the non-fixated surgical templates. ConclusionThe results of this study indicate that significant deviation has to be taken into account when placing cranio-maxillofacial implants using skin-supported surgical templates. Surprisingly, the use of bone-fixated pins worsened the accuracy.

A new saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the Upper Cretaceous of Shandong, China.

A new saurolophine hadrosaurid, Laiyangosaurus youngi gen. et sp. nov. is described and phylogenetically analyzed based on several cranial elements from the Jingangkou Formation, Wangshi Group, Upper Cretaceous of Laiyang, Shandong, China. Laiyangosaurus youngi differs from other members of the saurolophine clade on the basis of a number of autapomorphies, including a prominent and narrow ridge on the lateral side of the nasal which forms the posterodorsal and posterior margin of the circumnasal depression, a primary ridge that runs along most of the maxillary tooth row that is slightly deflected posteriorly, a retroarticular process of the surangular that is dorsolateroposteriorlly recurved, and orbital margins that are wider than the infratemporal margins of the jugal. This new taxon can be further distinguished by a number of unique combination of characters, including dorsal margin of nasal is flat, absence supracranial crest, a relatively shallow and rostrodorsally directed caudal margin of the lacrimal process of the jugal, and one or more foramina present on the rostral surface of the premaxilla. A phylogenetic analysis indicates that L. youngi comprises a monophyletic clade, which is known as Edmontosaurini.

Anatomical Parameters of the Nasolacrimal Duct in Healthy Children Measured with Computed Tomography.

Objectives:This study is an evaluation of anatomical parameters at different levels of the bony nasolacrimal duct (NLD) in healthy children of different age groups using computed tomography (CT) measurements.Methods:Bony NLD CT images of 289 patients aged 0-15 years who presented at the emergency department with various indications and underwent a brain CT scan were retrospectively evaluated. The anterior-posterior and transverse diameter at the inferior orbital margin, the narrowest diameter of the NLD, NLD length, and the orientation angle in the sagittal plane (the angle between the line connecting the distal and proximal ends of the NLD and a line drawn parallel to the nasal floor) were analyzed by age group.Results:The anterior-posterior and transverse diameters at the level of the inferior orbital margin and the NLD length recorded in sagittal CT images were statistically significantly greater in patients older than 5 years of age (p<0.05). While there was an increase in the narrowest diameter of the NLD beginning at the age of 3 years, it was not statistically significant (p=0.25). The degree of the angle between the central line and the nasal floor did not change significantly between the groups. (p>0.05).Conclusion:A greater anterior-posterior diameter, transverse diameter, narrowest diameter of the NLD, and NLD length were observed with increasing age. The NLD anatomical parameters that we have identified in healthy children may serve as an important and useful guide in determining locations of the NLD and selecting surgical instruments of appropriate size and diameter before NLD surgery.

Position and size of the sphenoid door jamb in the lateral orbital wall for the orbital decompression.

The aim of this study was to identify the three-dimensional topography of the sphenoid door jamb (SDJ) in the lateral orbital wall and to propose navigational guidelines for safe deep lateral decompression using surgical landmarks. The 120 orbits and SDJs of 60 subjects were three-dimensionally reconstructed using Mimics software. The mean volumes of the orbit and SDJ were 24.3 mm3 and 2.0 mm3, respectively. The mean distances from the lateral orbital margin (LOM) to the anterior and posterior margins of the SDJ were 13.2 and 36.3 mm, respectively. The mean distances from the superior orbital fissure to the LOM and to the posterior margin of the SDJ were 40.2 mm and 4.6 mm, respectively. The mean distances from the inferior orbital fissure (IOF) to the anterior and posterior margins of the SDJ were 3.8 mm and 20.5 mm, respectively. In the superior approach of the orbit, it can be predicted that the area up to 3 cm posterior from the LOM is safe, while 1 cm posterior from the safe zone could be a dangerous zone. In the inferior approach of the orbit, the safe area will be about 1 cm posterior from the anterior tip of the IOF, and the area up to 1 cm posterior from the safe zone should be approached with extreme care.

Chloroma of the orbit as a presenting feature of acute myeloid leukemia in a four year old female child

A four year old female child presented with a painless swelling of the right lower lid for 25days, which was progressively increasing in size. On palpation, a firm nodular mass just above the inferior orbital margin was noted. MRI showed homogenous enhancing mass in the orbit. Progressive axial proptosis developed in 8 days, with inability to close the eye. Bone marrow aspiration at this stage revealed Acute Myeloid Leukemia. Chemotherapy was started. Bone marrow picture after 10days showed remission phase. Symptoms and signs began to regress. The child was discharged on maintenance chemotherapy; but was admitted 3weeks later with fever; the child expired after admission 2 days due to secondary infection.

Insights into cranial morphology and intraspecific variation from a new subadult specimen of the pan-cheloniid turtle &lt;em&gt;Euclastes wielandi&lt;/em&gt; Hay, 1908

We describe a nearly complete skull and mandible of a subadult of Euclastes wielandi, a pan-cheloniid turtle recently recovered at the Jean and Ric Edelman Fossil Park at Rowan University in Mantua Township, New Jersey, which yields new information about the osteology, ontogeny, and intraspecific variation of this taxon. The specimen was collected from the earliest Danian Main Fossiliferous Layer (MFL) of the Hornerstown Formation. Although discovered immediately adjacent to remains of two pleurodires, Taphrosphys sulcatus and Bothremys sp., the skull and mandible can be definitively assigned to Pan-Cheloniidae based on its V-shaped basisphenoid and rod-like rostrum basisphenoidale. Among three pan-cheloniid taxa known from the MFL, the specimen is assigned to Eu. wielandi based on its low skull with dorsally-directed orbits, symphyseal swelling in the mandibular triturating surface, and high dorsum sellae. Comparisons with other specimens of Eu. wielandi and adults and juveniles of other pan-cheloniids revealed variations in the type and timing of cranial ontogenetic changes in the clade, as well as anatomical traits subject to intraspecific variation, such as the depth of the sella turcica, paths of the foramina nervi hypoglossi, and development of a precolumellar fossa. The relative contribution of the frontal to the orbital margin and precise path of the prefrontal-supraorbital scale sulcus are subject to individual variation in Eu. wielandi, as well as ontogenetic variation and bilateral asymmetry in other cryptodirans, signifying that the widespread use of frontal retraction in taxon diagnoses and as a phylogenetic character should be reconsidered. As in multiple other taxa, the mandibular triturating surface expands through growth in Eu. wielandi, demonstrating that increased durophagy with age was a common life strategy among Cryptodira.

Two- versus Three-Point Internal Fixation of Displaced Zygomaticomaxillary Complex Fractures.

Despite the high frequency of the zygomaticomaxillary complex (ZMC) fractures, there is no consensus among facial reconstructive surgeons regarding the best surgical management; thus, surgical choice for ZMC fractures is still challenging. This study included 40 patients with displaced ZMC fracture. Twenty patients were treated with open reduction and internal fixation (OR/IF) using two-point fixation technique (at infraorbital margin and zygomaticofrontal buttress region) and the remaining 20 patients were treated with OR/IF using three-point fixation technique (at frontozygomatic suture, infraorbital margin, and zygomatico maxillary buttress). The results of both types of ZMC fractures repair were then statistically compared. No statistical differences between the two types regarding malar eminence asymmetry; projection (forward displacement) and width (medial displacement) in axial CT; inferior displacement; superior displacement and width (medial displacement) in coronal CT; angle of displacement (outward displacement) in 3D CT; masseter and temporalis muscles power electromyography; actual duration of surgery; and patient satisfaction. On the other hand, the total cost of the used plates and screws was significantly higher with three-point repair than two-point repair ( p = 0.003). Moreover, postoperative CT lateral zygoma displacement was statistically significantly better in three-point fixation. Two-point fixation modality for displaced ZMC fractures is as effective as three-point method in fixation and prevents postreduction rotation or clinical displacement with significantly lower cost.

Pterocryptis subrisa, a new silurid catfish (Teleostei: Siluridae) from northeastern India.

Pterocryptis subrisa, a new species of silurid catfish from the Kaladan River drainage in northeastern India, is described in this study. It can be distinguished from congeners by the unique combination of the following characters: supralabial fold extending posteriorly beyond vertical through posterior orbital margin; nearly circular eye; head length 17.6-19.6% SL; head depth 10.6-11.9% SL; dorsal-fin height 2.6-4.7% SL; 2 dorsal-fin rays; pectoral-fin length 11.8-14.0% SL; body depth at anus 14.4-16.7% SL; caudal peduncle depth 6.8-8.5% SL; 66-75 anal-fin rays; confluent anal and caudal fins separated by deep notch; 17 principal caudal-fin rays; and 57 vertebrae. The generic status of Pterocryptis taytayensis is discussed, with this species being reassigned to Ompok.

Planes of Reference for Orbital Fractures: A Technique for Reproducible Measurements of the Orbit on Computed Tomography Scans.

Planes of reference for orbital fractures (PROF) was developed to standardize measurements made on orbital computed tomography scans. This study describes the use of PROF in determining the location along the orbital floor where the posterior ledge (PL) most commonly occurs. The transverse inclination and anterior-posterior inclination of the orbital floor will also be measured. This study evaluates 104 patients with unilateral orbital fracture. Fifty-two patients had intact infra-orbital margin (IM) and 52 had fractured IM. Facial computed tomography scans were analyzed using Osirix Lite Digital Imaging and Communications in Medicine Viewer version 7.0.1 (Geneva, Switzerland). All skull positions were standardized by orientation according to Frankfurt and mid-sagittal planes. Measurements of distance of PL from IM were determined in the sagittal view. Measurements of the inclination of the orbital floor in the transverse and anterior-posterior sections were done on the coronal and sagittal views respectively. For patients with intact and fractured IM, the mean distances of PL from IM were 22.1 mm (95% CI: 21.2-23.0) and 21.1 mm (95% CI: 20.2-21.9) respectively. Mean transverse inclination was 19.4° (95% CI: 18.3-20.5). Mean anterior-posterior inclination was 15.5° (95% CI: 14.5-16.5). Planes of reference for orbital fractures is a simple and effective method to acquire standardized measurements of the orbital cavity on computed tomography scans. Understanding the commonest location of PL and the orientation of the orbital floor in 3-dimensional space allows surgeons to perform dissection with greater precision.

Morphometric analysis of infraorbital foramen in South Indian dry skulls

Objective- The infraorbital foramen is located on the maxillary bone 1 cm under the infraorbital margin. Infra orbital nerve blocks are done in children for managing the postoperative pain which can occur after cleft lip operation and endoscopic sinus operation. Infraorbital nerve can also be damaged in cases of zygomatic complex fractures which are one of the most common facial injuries. So, this study was undertaken to analyze the anatomical variations by comparing various morphometric measurements of infraorbital foramen in dry skulls of adult South Indian population.Materials and methods- 60 dry skulls of unknown sex were used for the study. Various measurements and distance from various surgical landmarks were measured to evaluate the location of infraorbital foramen on both sides. Statistical Analysis was done for the above measurements mean and standard deviation, median, range, and mode were calculated.Results: The mean distance of infraorbital foramen from piriform aperture, lower end of alveolus of maxilla and infraorbital margin was 18.39, 27.88 and 7.09mm on the right and 17.89, 27.31 and 6.95mm on the left side. The mean vertical and horizontal diameter was 3.78 and 3.50mm on the right side and 3.48 and 3.35mm on the left side. In our study, the most common site of IOF in Indian skulls was found to be in line with the second premolar tooth (59.01%), followed by its position between the first and second premolar tooth (27.87%).Conclusion- These results will be helpful for surgeons while doing maxillofacial surgery and regional block anesthesia.Bangladesh Journal of Medical Science Vol.17(4) 2018 p.562-566

Pseudanthias emma new species, with notes on a collection of anthiadine serranid fishes from off Myanmar (eastern Indian Ocean).

Recent exploratory trawling off the coast of Myanmar by the R/V Dr Fridtjof Nansen has resulted in the collection of six species of anthiadine serranid fishes. Four of the species are represented by specimen vouchers: Pseudanthias emma sp. nov., P. gibbosus (Klunzinger), Odontanthias rhodopeplus (Günther) and Plectranthias sp. 1. The remaining two species are represented only by photographs: Plectranthias sp. 2 and Sacura sanguinea Motomura, Yoshida Vilasri. Pseudanthias emma is described from the 107 mm SL holotype. It is distinguished from congeners in having the following combination of characters: dorsal rays X,16; pectoral rays 18; lateral-line scales 42; third dorsal-fin spine longest, prolonged; no papillae on posterior margin of orbit; soft part of dorsal with low scaly sheath; subopercle and interopercle indistinctly serrated; caudal fin weakly concave centrally, with elongate filaments extending from second to uppermost and second to lowermost branched rays. Plectranthias sp. 1 is a probable new species closely allied to P. sagamiensis (Katayama), from which it appears to differ in having fewer segmented dorsal rays and fewer rows of cheek scales. Plectranthias sp. 2 is a probable new species closely allied to P. alcocki Bineesh, Akhilesh, Gopalakrishnan Jena, from which it appears to differ in lacking a large black spot on the operculum and dusky ventral spot on the abdomen. New character, habitat and distribution information is provided for all six species. Pseudanthias vizagensis Krishna, Rao Venu is suggested as a probable junior synonym of P. pillai Heemstra Akhilesh.

Spatial distributions and environmental relationships of two species complexes of freshwater atyid shrimps

AbstractKnowledge of cryptic species distributions and their relationships with environmental factors may be extremely valuable for biodiversity conservation. In freshwater ecosystems, morphologically cryptic species often have different geographic distributions that can overlap to varying extents. The importance of differential species responses to environmental conditions in determining their spatial distributions is, however, unclear. Here, we evaluated the importance of species responses to environmental drivers, in particular the physicochemical factors, in the spatial distributions and environmental relationships of two shrimp species complexes Caridina indistincta Calman, 1926 and Paratya australiensis Kemp, 1917. We analyzed shrimp specimens from 89 sites in 17 catchments across South‐East Queensland by sequencing a fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) to identify individuals. Furthermore, although there is evidence that morphologically the cryptic species of these shrimps differ very little, we made detailed morphological assessments to combine with molecular data, hoping to be able to distinguish among the species more easily and cheaply for future studies. There were significant morphological differences among the three cryptic species of the C. indistincta species complex, specifically in carapace length (cl), number of dorsal teeth (nDt), number of ventral teeth (nVt), teeth posterior to orbital margin (TPOM), and the calculated ratios A/rl, and rl/cl, while the two lineages of the P. australiensis species complex differed in the number of dorsal teeth (nDt) and the calculated ratios of A/rl, rl/cl, and rh/ch. To determine the importance of species responses in explaining the spatial distribution of cryptic species based on the species‐variables relationships, a redundancy analysis (RDA) was used to summarize these relationships. This ordination analysis showed distinct differences among cryptic species in their correlation with water quality variables and elevation. C. indistincta sp. B and C. indistincta sp. D were significantly associated with elevation and dissolved oxygen range, respectively. As well, P. australiensis lineages 4 and 6 were significantly correlated with elevation and conductivity, respectively. Overall, our results demonstrated the advantage of using analyses of biotic and abiotic variables as a valid approach for defining species responses to abiotic factors in cryptic species of atyid freshwater shrimps.

Accuracy of two midsagittal planes in three-dimensional analysis and their measurement in patients with skeletal mandibular deviation: a comparative study

Our aim was to evaluate the accuracy of two midsagittal planes (MSP) to provide a better reference plane for studying the 3-dimensional structural symmetry in patients with skeletal mandibular deviation. Thirty adult patients with facial asymmetry were admitted to the Department of Orthodontics, Hospital of Stomatology, between January 2015 and 2017. The DICOM data were collected and reconstructed using ProPlan CMF® 2.0 (Materialise). Two sets of reference planes were set up. In the orbital margin plane group, the plane crossing the nasion (N) point and perpendicular to the frontozygomatic (FZ) suture line was used as the MSP. In the skull base plane group, the MSP was established using the sella turcica (S), N, and basion (Ba). The distances from the craniofacial skeletal and soft tissue midline landmarks to the two MSP were separately measured, and the significance of differences between measurements corresponding to two reference planes were assessed using the paired t test. Except for the posterior nasal spine (PNS)-MSP, the distances from other soft and hard tissue landmarks to the MSP in the orbital margin plane group were significantly shorter than those in the skull base plane group. In the 3-dimensional measurement analysis, the skeletal and soft tissue anatomical midline landmarks were closer to the MSP in the orbital margin plane group. The MSP crossing point N, perpendicular to the FZ suture line, was more accurate and suitable.

Avaliação da prevalência de células de Haller e sua relação com alterações maxilofaciais

Introdução: As células de Haller são descritas como células etmoidais aeradas, localizadas na margem inferior da órbita, próximas aos óstios dos seios maxilares. A tomografia computadorizada de feixe cônico (TCFC) tem amplo uso na odontologia, permitindo aquisição de imagens da região craniofacial. Objetivo: Identificar, em exames de TCFC, a relação da célula de Haller com as seguintes condições: sinusopatia, desvio de septo nasal ósseo, tratamento endodôntico e lesões periapicais. Materiais e métodos: Foram utilizados 99 exames de TCFC, sendo 51 incluídos nos critérios da pesquisa. As imagens foram analisadas no software Xelis Dental®, de maneira a identificar a presença ou não da célula de Haller, bem como sua relação com as condições citadas. Resultados: Dentre os 51 exames de TCFC avaliados, 35,3% apresentaram célula de Haller do lado direito e 23,5% no lado esquerdo. Levando-se em conta a relação das células de Haller com uma ou mais alterações aqui citadas, no lado direito a tivemos em 72% dos casos, enquanto no lado esquerdo tal relação se fez presente em 75% dos casos. Conclusão: Exames de TCFC que apresentam a margem infraorbital permitem verificar a presença ou ausência da célula de Haller. Nessa amostra, verificamos maior presença de casos de endodontia, desvio de septo e sinusopatia nos indivíduos que apresentaram células de Haller.

An enigmatic crocodyliform from the Upper Cretaceous Quseir Formation, central Egypt

Non-marine vertebrates, including many crocodyliform clades, remain poorly documented from uppermost Cretaceous deposits of Africa. Recent exploratory fieldwork in the Upper Cretaceous (middle Campanian) Quseir Formation exposed around Dakhla Oasis (Western Desert of Egypt) has revealed new fossils from continental and marginal marine settings that include abundant crocodyliform remains. In particular, materials of an enigmatic crocodyliform, Wahasuchus egyptensis gen. et sp. nov., represented by both cranial and postcranial remains, suggest the presence of a novel southern Tethyan crocodyliform assemblage from northern Africa during the Late Cretaceous. Materials recovered of this taxon thus far include fragmentary portions of the skull and mandible, amphicoelous dorsal vertebrae, and fragmentary appendicular remains. This form is distinguished by a number of unique features including a domed platyrostral skull; a strongly festooned lateral margin of the maxilla with two waves of tooth enlargement; a deep, sculptured fossa at the base of the postorbital bar; a jugal with an anterior process that is at least three times broader than the posterior process; an orbital margin dorsally overlapping the lateral temporal fenestra; a supraoccipital with a distinct medial tuber and associated ventral fossa; and a robust straight dentary with contribution of the splenial to the symphysis. This new form suggests a potentially unique Late Cretaceous assemblage from northern Africa, markedly different from better-known Late Cretaceous crocodyliform assemblages of South America and Madagascar, or from earlier (pre-Turonian) deposits in Africa. This pattern may reveal a distinct regional fauna along the southern Tethys, or potential Cretaceous relationships with Eurasian neosuchian-dominated assemblages.

The prevalence of the accessory infraorbital foramen among sexes: preliminary results.

BRANIGAN L. MCGOWAN, DALTON S. BOLON, Dept of Natural Sciences &amp; Mathematics, West Liberty University, West Liberty, WV, 26074, and MATTHEW J ZDILLA, Depts of Natural Sciences &amp; Mathematics and Graduate Health Sciences, West Liberty University, West Liberty, WV, 26074 and Dept of Pathology, Anatomy, and Laboratory Medicine (PALM), West Virginia University School of Medicine, Morgantown, WV, 26506. The prevalence of the accessory infraorbital foramen among sexes: preliminary results.The infraorbital foramen is an opening in the maxillary bone below the infraorbital margin of the orbit through which the maxillary nerve travels. The infraorbital foramen is particularly important in nerve block procedures. Occasionally, an accessory infraorbital foramen may be present, complicating nerve block procedures. Therefore, this study assessed the prevalence of the accessory infraorbital foramen among sexes. A total of 565 crania of known sex were assessed (301 males and 264 females). In the total population, 108 of 565 crania (19.1%) were found to have an accessory IOF. With regard to sex, 66 of 301 males (21.9%) and 42 of 264 females (15.9%) were found to have an accessory IOF. The results of this study underscore the importance of screening for the accessory infraorbital foramen in both males and females prior to infraorbital nerve block.

Facial approximations: Characteristics of the eye in a South African sample

Although guidelines for facial approximations, including those for the eye, are in use in South Africa, limited data on African populations exist to confirm its validity. As precise placement of the eyes in facial approximations is of importance for facial recognition, this study tested established guidelines by measuring specific instrumental dimensions. Forty-nine cadavers from the Sefako Makgatho Health Sciences University and the University of Pretoria were dissected to determine the position of the canthi and the size and position of the eyeball in the orbit. Thirty cone beam computer tomography scans and 30 computer tomography scans from the Oral and Dental and Steve Biko Hospitals respectively were used to determine the size of the eyeball. Results from this study were compared to the published guidelines. The most prominent discrepancies included a more rectangular shape of the orbit, an oval shaped eyeball and a different position of the canthi. In African faces, the medial canthus was found to be located higher than the lateral canthus. The distance between the endocanthion and superior orbital margin was 17.7mm and the exocanthion and superior orbital margin 19.5mm. Inter-population differences may have an effect on facial approximations and its accuracy as is often demonstrated in practice. The findings of this study should be taken into consideration when designing population specific guidelines for reconstruction of the eye in South Africans of African ancestry.

Cranial and postcranial anatomy of Cacops morrisi, a eucacopine dissorophid from the early Permian of Oklahoma

ABSTRACTThe armored dissorophid Cacops morrisi is one of many anamniote taxa preserved at the speciose early Permian karst deposit near Richards Spur, Oklahoma. The taxon was previously known only from two isolated skulls representing a juvenile individual and an adult individual. Here we describe one partial and two complete new skulls of juvenile and subadult individuals of C. morrisi that represent intermediately sized individuals compared with previously documented skulls, as well as the first description of the postcrania of the taxon. The primary objectives of this paper are to expand upon the brief original description of the cranial material and to provide the first description of the postcrania of C. morrisi for comparison with other dissorophids. The new data improve the resolution of the ontogenetic series of the taxon through refined temporal constraints on major ontogenetic changes of the cranial region (e.g., closure of the otic notch, transition in lateral skull profile), contribute new information regarding the neurocranium, and improve our understanding of dissorophid postcrania. We also identify several new diagnostic features, such as the presence of uncinate processes on the ribs (previously unknown in the genus) and the exclusion of the lacrimal from the orbital margin (unique among dissorophids).Citation for this article: Gee, B. M., and R. R. Reisz. 2018. Cranial and postcranial anatomy of Cacops morrisi, a eucacopine dissorophid from the early Permian of Oklahoma. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1433186.