A Comparison of Common Hippopotamus (Artiodactyla) and Mysticete (Cetacea) Nostrils: An Open and Shut Case

Hippos are considered the closest living relatives to cetaceans and they have some similar adaptations for aquatic living, such as a modified respiratory tract. Behavioral observations of male and female common hippos (Hippopotamus amphibius) at Disney's Animal Kingdom® and the Adventure Aquarium were conducted to describe and examine movements of the nostrils during respiration (inspiration, expiration, and inter-breath interval). The hippo nostril is a crescent shaped opening with lateral and medial aspects that are mobile and can be adducted and abducted to regulate the nostril opening. Notably, the default (resting) position of the nostrils is closed during the inter-breath interval, even when hippos are resting in water and their heads are not submerged. Similar to cetaceans, this aquatic adaptation protects the respiratory tract from an accidental incursion of water that can occur even when the nostrils are above water. Dissection of a deceased captive common hippo suggests there are separate muscles that pull the medial and lateral aspects for abduction. The internal nasal passage has a nasal plug that is similar in shape but less pronounced than the nasal plugs of two baleen whale species studied (minke whale Balaenoptera acutorostrata, fin whale Balaenoptera physalus). Examination of the musculature suggests fibers attach from the premaxillae and extend caudally to retract the plug to open the nasal passage. We discuss similarities and differences of the nostrils/blowholes of fully aquatic, semi-aquatic, and terrestrial species to assess adaptations related to environmental conditions that may be convergent or derived from a common ancestor. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:693–702, 2019. © 2018 Wiley Periodicals, Inc.     

The First Record of Incidences of Ankylosis in Seven Triplefin Fishes (Pisces: Tripterygiidae) from New Zealand

Different cases of vertebral ankylosis were examined in seven tripterygiid species obtained from waters around New Zealand. The skeletal deformities observed are located in the caudal region of the vertebral column. Those occurred in Forsterygion nigripenne, Matanui bathytaton and in one specimen of Ruanoho whero were severe cases. The mechanism of the formation of vertebral ankylosis and the causes behind such anomaly were discussed. Further studies are needed to relate specific pollutants with the observed types of deformities. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:39–45, 2018. © 2017 Wiley Periodicals, Inc.     

Mysticetes to MiniConference to Manuscripts: Introduction to Thematic Issue on Mysticete Anatomy

This issue of the Anatomical Record is focused on the theme of Mysticete Anatomy. There are six included articles that explore the anatomy of the nasal region (Marquez et al., 2018; Maust-Mohl et al., 2018), larynx (Damien et al., 2018), lungs (Fetherston et al., 2018), sublingual fascia (Werth et al., 2018), and brain (Raghanti et al., 2018). These papers document anatomical features exhibited by mysticetes (baleen whales) and their related cousins (including other whales, and the semiaquatic moose and hippopotamus). This theme stems from a 2-day MiniConference on Mysticete Anatomy, hosted at the Icahn School of Medicine at Mount Sinai in New York City on May 2016. Anatomy is explored in the contexts of function and evolution of aquatic adaptations. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc. Anat Rec, 302:663–666, 2019. © 2019 Wiley Periodicals, Inc.     

Novel reconstruction of the orientation of the pectoral girdle in sauropods

The orientation of the scapulocoracoid in sauropod dinosaurs is reconstructed based on comparative anatomical investigations of pectoral girdles of extant amniotes. In the reconstruction proposed here, the scapula of sauropods stands at an angle of at least 55° to the horizontal plane in mechanical coherence with the sternal apparatus including the coracoids. The coracoids are oriented cranioventrally to the rib cage and the glenoid is directed mediolaterally, which allows the humerus to swing in a sagittal plane. The inclination of the scapula to the horizontal plane is reconstructed for Diplodocus (60–65°), Camarasaurus (60–65°), and Opisthocoelicaudia (55–65°). The inclination of the scapulocoracoid has consequences for the overall body posture in Camarasaurus and Opisthocoelicaudia, where the dorsal contour would have ventrally declined toward the sacrum. Scapulocoracoid mobility depends on the arrangement of clavicles, the reconstruction of a coracosternal joint, and the reconstructed musculature of the shoulder girdle. In a crocodylian model of the shoulder musculature, m. serratus profundus and superficialis form a muscular sling, which suspends the trunk from the shoulder girdle and would allow a certain mobility of the scapulocoracoid. An avian model of the shoulder musculature would also mean suspension by means of the m. serratus complex, but indicates a closer connection of the scapula to the dorsal ribs, which would lead to more restricted movements of the scapulocoracoid in sauropods. Anat Rec, 290:32–47, 2007. © 2006 Wiley‐Liss, Inc.     

Ossification Pattern in Forelimbs of the Siamese Crocodile (Crocodylus siamensis): Similarity in Ontogeny of Carpus Among Crocodylian Species

Crocodylians have highly derived elongated carpus, which is related to their use of forelimbs in many types of gaits as well as in burrowing. The objective of present study was to describe the ossification of the forelimb in five stages of Siamese crocodile (Crocodylus siamensis). The ossification begins approximately at stage 20 in arm and forearm bones moving sequentially to the metacarpal elements. The first carpal elements with ossification centers are radiale + intermedium and ulnare (stage 22–23), and their ossification mode is typical of long bones. Between stages 22 and 24 distal carpals 3, 4, and 5 fuse together to a single formation. In the stage 25, the ossification proceeds to the pisiform, which starts ossifying late during the embryogenesis. The phalangeal formula of the digits is 2,3,4,5,3. Although there are some interspecific differences, it appears that all crocodylians have similarly uniform skeletal pattern, the process of ossification, number of carpal elements and phalangeal formulas probably due to their similar lifestyles. Anat Rec, 301:1159–1168, 2018. © 2018 Wiley Periodicals, Inc.     

An Analysis of Extraocular Muscle Forces in the Piked Dogfish (Squalus acanthias)

Vertebrates utilize six extraocular muscles that attach to a tough, protective sclera to rotate the eye. The goal of the study was to describe the maximum tetanic forces, as well as the torques produced by the six extraocular muscles of the piked dogfish Squalus acanthias to understand the forces exerted on the eye. The lateral rectus extraocular muscle of Squalus acanthias was determined to be parallel fibered with the muscle fibers bundled into discrete fascicles. The extraocular muscles attach to the sclera by muscular insertions. The total tensile forces generated by the extraocular muscles ranged from 1.18 N to 2.21 N. The torques of the extraocular muscles ranged from 0.39 N to 2.34 N. The torques were greatest in the principal direction of movement for each specific muscle. The lateral rectus produced the greatest total tensile force, as well as the greatest torque force component, while the medial rectus produced the second greatest. This is likely due to the constant rotational movement of the eye anteriorly and posteriorly to stabilize the visual image, as well as increase the effective visual field during swimming. Rotational forces in dimensions other than the primary direction of movement may contribute to motion in directions other than the principal direction during multi-muscle contraction that occurs in the vertebrate eye. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:837–844, 2019. © 2018 Wiley Periodicals, Inc.     

Natural development of dermal ectopic bone in the american alligator (Alligator mississippiensis) resembles heterotopic ossification disorders in humans

Heterotopic ossification (HO) occurs when soft tissues are inappropriately converted to bony tissue. Several human diseases result in HO with few reliable treatment options. Animal models that naturally produce dermal ectopic bone (i.e., osteoderms), such as crocodilians, have never been utilized as models for studying these disorders in humans. Here, a histological evaluation and staging criteria for osteoderm development is described for the first time in the American alligator (Alligator mississipiensis). Differential staining and immunohistochemistry of alligator scales depict a progressive change during development, where woven bone forms from the differentiated dermis. Bone formation proceeds via intramembranous ossification, which is initiated in part by endothelial cell precursors that undergo endothelial‐to‐mesenchymal transition and eventually acquire an osteoblast phenotype. As such, the development of osteoderms in the American alligator bears morphological and mechanistic similarities to HO in humans, presenting a potential model for future study of soft tissue mineralization pathologies and providing insight into the morphological and molecular development of osteoderms in other vertebrate lineages. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:56–76, 2018. © 2017 Wiley Periodicals, Inc.     

Vertical Clinging and Leaping Ahead: How Bamboo Has Shaped the Anatomy and Physiology of Hapalemur

Hapalemur sps. and Prolemur simus (bamboo lemurs, collectively) stand out from the relatively homogeneous lemurids because they are bamboo feeders and vertical clingers and leapers. This unique diet presents equally unique challenges, like its verticality, toughness, and toxicity. The bamboo lemurs share the generalized anatomy of the other lemurids, but also display some well-documented skeletal adaptations, perhaps to overcome the problems presented by their specialization. Soft-tissue adaptations, however, remain largely unexplored. Explored here are possible soft-tissue adaptations in Hapalemur griseus. We compare H. griseus with other lemurids, Propithecus, Galago, Tarsier, and a tree shrew. Based on the available anatomical and physiological data, we hypothesize that Hapalemur and Prolemur species will have differences in hindlimb morphology when compared with other lemurids. We predict that H. griseus will have more hindlimb muscle mass and will amplify muscle mass differences with increased type II muscle fibers. Relative hindlimb muscle mass in H. griseus is less than other prosimians sampled, yet relative sural muscle mass is significantly heavier (P < 0.01) in H. griseus. Results show that the soleus muscle of H. griseus has a higher amount of type II (fast) fibers in plantarflexors. These findings indicate although H. griseus shares some generalized lemurid morphology, its diet of bamboo may have pushed this generalized lemurid to an anatomical extreme. We suspect additional bamboo-specific adaptations in their anatomy and physiology will be uncovered with further examination into the anatomy of the bamboo lemurs. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc. Anat Rec, 303:295–307, 2020. © 2019 American Association for Anatomy     

Restoring Maximum Vertical Browsing Reach in Sauropod Dinosaurs

The ongoing controversy centered on neck posture and function in sauropod dinosaurs is misplaced for a number of reasons. Because of an absence of pertinent data it is not possible to accurately restore the posture and range of motion in long necked fossil animals, only gross approximations are possible. The existence of a single “neutral posture” in animals with long, slender necks may not exist, and its relationship to feeding habits is weak. Restorations of neutral osteological neck posture based on seemingly detailed diagrams of cervical articulations are not reliable because the pictures are not sufficiently accurate due to a combination of illustration errors, and distortion of the fossil cervicals. This is all the more true because fossil cervical series lack the critical inter‐centra cartilage. Maximum vertical reach is more readily restorable and biologically informative for long necked herbivores. Modest extension of 10° between each caudal cervical allowed high shouldered sauropods to raise the cranial portion of their necks to vertical postures that allowed them to reach floral resources far higher than seen in the tallest mammals. This hypothesis is supported by the dorsally extended articulation of the only known co‐fused sauropod cervicals. Many sauropods appear to have been well adapted for rearing in order to boost vertical reach, some possessed retroverted pelves that may have allowed them to walk slowly while bipedal. A combination of improved high browsing abilities and sexual selection probably explains the unusually long necks of tall ungulates and super tall sauropods. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:1802–1825, 2017. © 2017 Wiley Periodicals, Inc.     

Postcranial Skeletal Differences in Free-Range and Captive-Born Primates

Skeletal morphology is important in evolutionary, genetic, developmental, physiological, and functional studies. Although samples from free-ranging individuals may be preferable, constraints of sample size, demography, or conservation status may necessitate the inclusion of captive-born individuals. Captivity may be associated with physical, physiological, or behavioral differences that may affect skeletal form. This study assesses differences in postcranial skeletal form between free-range and captive-born Macaca mulatta and Saguinus oedipus. Samples included free-range M. mulatta from Cayo Santiago (Caribbean Primate Research Center) and captive-born macaques from the Wisconsin National Primate Research Center. S. oedipus samples included free-range born and captive-born individuals from the Oak Ridge Associated Universities Marmoset Research Center. Twenty-four dimensions of various bones, including the scapula, upper limb, innominate and lower limb, were recorded for adults. Age of epiphyseal closure was recorded for immature captive-born M. mulatta. Analysis of variance and principal component analyses tested significant differences between free-range born and captive-born individuals in each species. Significant differences were present in size and shape of postcrania between free-range and captive-born within taxa. Free-range macaques were larger than captive-born macaques, but this pattern did not consistently carry over to the Saguinus samples. Shape differences, while present throughout the skeleton, were especially prominent in the scapula. Differences in developmental timing, nutrition, and physical activity can be expected to contribute to the observed differences in postcranial skeletal form. These differences should be considered when captive-born primates are included in morphological or evolutionary studies. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:761–774, 2019. © 2018 Wiley Periodicals, Inc.     

Is Salamander Limb Regeneration Really Perfect? Anatomical and Morphogenetic Analysis of Forelimb Muscle Regeneration in GFP‐Transgenic Axolotls as a Basis for Regenerative,Developmental, and Evolutionary Studies

The axolotl Ambystoma mexicanum is one of the most commonly used model organisms in developmental and regenerative studies because it can reconstitute what is believed to be a completely normal anatomical and functional forelimb/hindlimb after amputation. However, to date it has not been confirmed whether each regenerated forelimb muscle is really a “perfect” copy of the original muscle. This study describes the regeneration of the arm, forearm, hand, and some pectoral muscles (e.g., coracoradialis) in transgenic axolotls that express green fluorescent protein (GFP) in muscle fibers. The observations found that: (1) there were muscle anomalies in 43% of the regenerated forelimbs; (2) however, on average in each regenerated forelimb there are anomalies in only 2.5% of the total number of muscles examined, and there were no significant differences observed in the specific insertion and origin of the other muscles analyzed; (3) one of the most notable and common anomalies (seen in 35% of the regenerated forelimbs) was the presence of a fleshy coracoradialis at the level of the arm; this is a particularly outstanding configuration because in axolotls and in urodeles in general this muscle only has a thin tendon at the level of the arm, and the additional fleshy belly in the regenerated arms is strikingly similar to the fleshy biceps brachii of amniotes, suggesting a remarkable parallel between a regeneration defect and a major phenotypic change that occurred during tetrapod limb evolution; (4) during forelimb muscle regeneration there was a clear proximo‐distal and radio‐ulnar morphogenetic gradient, as seen in normal development, but also a ventro‐dorsal gradient in the order of regeneration, which was not previously described in the literature. These results have broader implications for regenerative, evolutionary, developmental and morphogenetic studies. Anat Rec, 297:1076–1089, 2014. © 2014 Wiley Periodicals, Inc.     

RETRACTED: Physcion 8-O-β-Glucopyranoside Exerts Anti-Tumor Activity Against Non-Small Cell Lung Cancer by Targeting PPARγ

Lung cancer is one of the most common causes of cancer related mortality. The present study is designed to investigate whether a naturally occurring anthraquinone compound, physcion 8-O-β-glucopyranoside (PG) could exert anti-cancer activity against non-small cell lung cancer (NSCLC). Cell viability was determined by Cell Counting Kit-8 (CCK-8) assay. Cell cycle distribution and cell apoptosis were determined by flow cytometry. Expressions of marker proteins were assessed by western blot analysis. To examine the role of PPARγ (peroxisome proliferator-activated receptor γ) in PG-induced apoptosis and cell cycle arrest, PPARγ was knockdown using siRNA. In addition, a xenograft model was established to investigate the effect of PG in vivo. The results showed that PG markedly induced cell cycle arrest and apoptosis in human NSCLC cell lines A549 and H358. The anti-tumor effect of PG in NSCLC cells was mediated by upregulation of PPARγ. Besides, in NSCLC cell lines, the anti-cancer activity of PG was also examined in the xenograft mice model, which showed that PG could significantly reduce tumor burden and activate apoptotic signaling. Our results demonstrated that PG can be regarded as a candidate chemotherapeutic agent for lung cancer. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:785–793, 2019. © 2018 Wiley Periodicals, Inc.     

Anatomy of Shoulder Girdle Muscle Modifications and Walking Adaptation in the Scaly Chinese Pangolin (Manis Pentadactyla Pentadactyla: Pholidota) Compared with the Partially Osteoderm‐Clad Armadillos (Dasypodidae)

Because pangolins are unique mammals with a body and limbs almost entirely sheathed in hard keratinous overlapping scales and with digging and climbing abilities, the shoulder girdle muscles may differ significantly from those of other mammals including the partially osteoderm‐clad armadillos. Therefore, we conducted a functional anatomical study of the shoulder girdle muscles in Chinese pangolins (Manis pentadactyla pentadactyla, Pholidota) and some armadillo species (Dasypodidae). Our CT scans revealed that the pangolin's overlapping scales are hard structures completely encasing the limbs. The armadillo's limbs, however, are covered with small relatively soft non‐overlapping scales embedded in the skin, and articulate completely free of the hard osteodermal carapace. The attachments of some shoulder girdle muscles in the pangolin have moved from the surrounding edges of the scapula to the spine, and they, therefore, fully cover the scapula. In addition, some pangolin shoulder girdle muscles cross the shoulder joint to insert on the distal humerus, but this does not occur in armadillos. We cannot rule out the possibility that these muscle modifications represent adaptations for digging and/or climbing in pangolins. Our results and previous literature do not establish specific links between them and locomotive modes. However, we propose that the Chinese pangolin may use its derived muscular features when walking to move its armor‐restricted forelimbs more effectively by swinging its head from side to side. Anat Rec, 298:1217–1236, 2015. © 2015 Wiley Periodicals, Inc.     

The Role of Ellis‐Van Creveld 2(EVC2) in Mice During Cranial Bone Development

EvC syndrome is a type of autosomal‐recessive chondrodysplasia. Previous case studies in patients suggest abnormal craniofacial development, in addition to dwarfism and tooth abnormalities. To investigate how craniofacial development is affected in EvC patients, surface models were generated from micro‐CT scans of control mice, Evc2 global mutant mice and Evc2 neural crest‐specific mutant mice. The anatomic landmarks were placed on the surface model to assess the morphological abnormalities in the Evc2 mutants. Through analyzing the linear and angular measurements between landmarks, we identified a smaller overall skull, shorter nasal bone, shorter frontal bone, and shorter cranial base in the Evc2 global mutants. By comparing neural crest‐specific Evc2 mutants with control mice, we demonstrated that the abnormalities within the mid‐facial regions are not accounted for by the Evc2 mutation within these regions. Additionally, we also identified disproportionate length to width ratios in the Evc2 mutants at all levels from anterior to posterior of the skull. Overall, this study demonstrates a more comprehensive analysis on the craniofacial morphological abnormalities in EvC syndrome and provides the developmental insight to appreciate the impact of Evc2 mutation within the neural crest cells on multiple aspects of skull deformities. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:46–55, 2018. © 2017 Wiley Periodicals, Inc.     

First Natural Endocranial Cast of a Fossil Snake (Cretaceous of Patagonia,Argentina)

In this study, we describe a natural endocranial cast included in a partially preserved medium‐sized skull of the Upper Cretaceous South American snake Dinilysia patagonica. The endocast is composed of sedimentary filling of the cranial cavity in which the posterior brain, the vessels, the cranial nerves, and the inner ear surrounded by delicate semicircular canals, are represented. It is simple in form, with little differentiation between the three main areas (Forebrain, Midbrain, and Hindbrain), and without flexures. The nervous system is well preserved. The posterior brain surface is smooth, except for two small prominences that make up the cerebellum. A large inner ear is preserved on the right side; it consists of a voluminous central mass, the vestibule, which occupies most of the space defined by the three semicircular canals. In particular, the lateral semicircular canal is very close to the vestibule. This characteristic, in combination with the medium to large body size of Dinilysia, its large skull and dorsally exposed orbits, and vertebrae bearing a rather high neural spine on a depressed neural arch, suggests that this snake would have had a semifossorial lifestyle. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:9–20, 2018. © 2017 Wiley Periodicals, Inc.     

Getting into Shape: Limb Bone Strength in Perinatal Lemur catta and Propithecus coquereli

Functional studies of skeletal anatomy are predicated on the fundamental assumption that form will follow function. For instance, previous studies have shown that the femora of specialized leaping primates are more robust than those of more generalized primate quadrupeds. Are such differences solely a plastic response to differential loading patterns during postnatal life, or might they also reflect more canalized developmental mechanisms present at birth? Here, we show that perinatal Lemur catta, an arboreal/terrestrial quadruped, have less robust femora than perinatal Propithecus coquereli, a closely related species specialized for vertical clinging and leaping (a highly unusual locomotor mode in which the hindlimbs are used to launch the animal between vertical tree trunks). These results suggest that functional differences in long bone cross-sectional dimensions are manifest at birth, belying simple interpretations of adult postcranial form as a direct record of loading patterns during postnatal life. Despite these significant differences in bone robusticity, we find that hindlimb bone mineralization, material properties, and measures of whole-bone strength generally overlap in perinatal L. catta and P. coquereli, indicating little differentiation in postcranial maturity at birth despite known differences in the pace of craniodental development between the species. In a broader perspective, our results likely reflect evolution acting during prenatal ontogeny. Even though primates are notable for relatively prolonged gestation and postnatal parental care, neonates are not buffered from selection, perhaps especially in the unpredictable and volatile environment of Madagascar. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 303:250–264, 2020. © 2018 American Association for Anatomy     

Adaptations of the Marsupial Newborn: Birth as an Extreme Environment

At birth a mammalian neonate enters an extreme environment compared to the intrauterine environment in which it has grown. This transition may be particularly extreme in marsupials because they are born at an exceedingly altricial state, after an exceptionally short gestation. Their stage of development must be considered embryonic by almost any criteria. Yet at this very early stage of development marsupials must travel to the teat, attach and suckle, and have basic functioning of all major physiological systems. In this article, we review the adaptations of the marsupial neonate for survival at an embryonic state, showing that the neonate exhibits a mosaic of accelerations and delays of various tissues and organs as well as several special adaptations to produce the functioning newborn. We then discuss the development of the craniofacial region, the body axis and limbs in order to detail some of the major changes to development leading to this uniquely configured neonate. We show that marsupial development arises out of a variety of heterochronies (changes in relative timing of events) and heterotopies (changes in location of specific developmental events) at the genetic, cellular and organ level. We argue that these data support hypotheses that many of the specific patterns seen in marsupial development arise from the basic constraint of embryonic energetic and tissue resources. Finally ideas on the evolutionary context of the marsupial developmental strategy are briefly reviewed. Anat Rec, 2019. © 2018 Wiley Periodicals, Inc. Anat Rec, 303:235–249, 2020. © 2018 American Association for Anatomy