First remingtonocetid archaeocete (Mammalia, Cetacea) from the middle Eocene of Egypt with implications for biogeography and locomotion in early cetacean evolution

2015 ◽  
Vol 89 (5) ◽  
pp. 882-893 ◽  
Author(s):  
Ryan M. Bebej ◽  
Iyad S. Zalmout ◽  
Ahmed A. Abed El-Aziz ◽  
Mohammed Sameh M. Antar ◽  
Philip D. Gingerich
Keyword(s):  
Middle Eocene ◽  
Lumbar Vertebrae ◽  
The Body ◽  
Power Stroke ◽  
Tethys Sea ◽  
Vertebral Centra ◽  
Hind Limbs ◽  
Caudal Vertebrae ◽  
Southern Tethys

AbstractRemingtonocetidae are Eocene archaeocetes that represent a unique experiment in cetacean evolution. They possess long narrow skulls, long necks, fused sacra, and robust hind limbs. Previously described remingtonocetids are known from middle Eocene Lutetian strata in Pakistan and India. Here we describe a new remingtonocetid, Rayanistes afer, n. gen. n. sp., recovered from a middle to late Lutetian interval of the Midawara Formation in Egypt. The holotype preserves a sacrum with four vertebral centra; several lumbar and caudal vertebrae; an innominate with a complete ilium, ischium, and acetabulum; and a nearly complete femur. The ilium and ischium of Rayanistes are bladelike, rising sharply from the body of the innominate anterior and posterior to the acetabulum, and the acetabular notch is narrow. These features are diagnostic of Remingtonocetidae, but their development also shows that Rayanistes had a specialized mode of locomotion. The expanded ischium is larger than that of any other archaeocete, supporting musculature for powerful retraction of the hind limbs during swimming. Posteriorly angled neural spines on lumbar vertebrae and other features indicate increased passive flexibility of the lumbus. Rayanistes probably used its enhanced lumbar flexibility to increase the length of the power stroke during pelvic paddling. Recovery of a remingtonocetid in Egypt broadens the distribution of Remingtonocetidae and shows that protocetids were not the only semiaquatic archaeocetes capable of dispersal across the southern Tethys Sea.

The Ligamentary System and the Segmental Musculature of Nephtys

1960 ◽  
Vol s3-101 (54) ◽  
pp. 149-176
Author(s):  
R. B. CLARK ◽  
M. E. CLARK
Keyword(s):  
Body Wall ◽  
The Body ◽  
Power Stroke ◽  
Coelomic Fluid ◽  
Unusual Structure ◽  
Shock Absorbers ◽  
Proximal Half ◽  
Unique System ◽  
Body Wall Muscles ◽  
The Impact

Nephtys lacks circular body-wall muscles. The chief antagonists of the longitudinal muscles are the dorso-ventral muscles of the intersegmental body-wall. The worm is restrained from widening when either set of muscles contracts by the combined influence of the ligaments, some of the extrinsic parapodial muscles, and possibly, to a limited extent, by the septal muscles. Although the septa are incomplete, they can and do form a barrier to the transmission of coelomic fluid from one segment to the next under certain conditions, particularly during eversion of the proboscis. Swimming is by undulatory movements of the body but the distal part of the parapodia execute a power-stroke produced chiefly by the contraction of the acicular muscles. It is suspected that the extrinsic parapodial muscles, all of which are inserted in the proximal half of the parapodium, serve to anchor the parapodial wall at the insertion of the acicular muscles and help to provide a rigid point of insertion for them. Burrowing is a cyclical process involving the violent eversion of the proboscis which makes a cavity in the sand. The worm is prevented from slipping backwards by the grip the widest segments have on the sides of the burrow. The proboscis is retracted and the worm crawls forward into the cavity it has made. The cycle is then repeated. Nephtys possesses a unique system of elastic ligaments of unusual structure. The anatomy of the system is described. The function of the ligaments appears to be to restrain the body-wall and parapodia from unnecessary and disadvantageous dilatations during changes of body-shape, and to serve as shock-absorbers against the high, transient, fluid pressures in the coelom, which are thought to accompany the impact of the proboscis against the sand when the worm is burrowing. From what is known of its habits, Nephtys is likely to undertake more burrowing than most other polychaetes.

scholarly journals BMD status of Postmenopausal Women in relation with BMI: A study with 93 cases

2016 ◽  
Vol 17 (2) ◽  
pp. 138-141
Author(s):  
Samira Sharmin ◽  
Mabubul Haque ◽  
Syedur Rahman Miah ◽  
Md Mahbub Ur Rahman ◽  
Jasmine Ara Haque ◽  
...  
Keyword(s):  
Lumbar Spine ◽  
Femoral Neck ◽  
Postmenopausal Women ◽  
Lumbar Vertebrae ◽  
The Body ◽  
Mineral Density ◽  
Cross Sectional ◽  
T Score ◽  
Minimal Trauma ◽  
The Mean

Objectives: Low bone mass is a common disorder in elderly population which predisposes to fracture with minimal trauma. This study was performed to find out the association between the Body Mass Index (BMI) and Bone Mineral Density (BMD) in postmenopausal women.Materials and Methods: This cross sectional study was carried out at Institute of Nuclear Medicine and Allied Sciences Comilla and Mitford, Dhaka over a period of 12 months from January 2013 to December 2013. A total 93 postmenopausal women were enrolled for this study. All postmenopausal women underwent a BMD scan of femoral neck and lumbar vertebrae using a Dual Energy X-ray Absorptiometry (DEXA). Participants were categorized into three groups according to their age and BMI. BMD were expressed base on T-score according to WHO criteria. The relation among BMI, age and BMD were assessed.Results: The results of this study showed that the mean age of the study group was 57.13±7.49 years with range of 46 to 75 years. The most postmenopausal women were in age group 55-65years. The mean BMI of the study subjects were 24.18±5.08 kg/m2 with a range of 15.62 to 36.20 kg/m2. Among 93 subjects osteopenia was greater at lumbar spine (45.2%) with T-score mean±SD-1.83±0.33 and osteoporosis at femoral neck (51.6%) with T-score mean ±SD-3.36±-0.67. Pearson’s correlation coefficient test showed inverse relationship between age and BMD both lumbar spine (r = -0.301, p = 0.003) and femoral neck (r = -0.303, p=0.003) whereas the positive relation between BMI and BMD both at lumbar spine (r=0.338, p=0.001) and femoral neck (r =0.343, p=0.001). These showed that with advancing age, BMD decreases and the risk of osteoporosis increases and with increasing BMI, BMD increases and risk of osteoporosis decreases.Conclusion: The findings of this study portrait that aging and low BMI are risk factors associated with bone loss. So preventive measure should be taken for high risk post menopausal women.Bangladesh J. Nuclear Med. 17(2): 138-141, July 2014

Caudofemoral musculature and the evolution of theropod locomotion

Paleobiology ◽  
1990 ◽  
Vol 16 (2) ◽  
pp. 170-186 ◽  
Author(s):  
Stephen M. Gatesy
Keyword(s):  
Knee Flexion ◽  
Hind Limb ◽  
The Body ◽  
Avian Evolution ◽  
Theropod Dinosaurs ◽  
Data Support ◽  
Caudal Vertebrae ◽  
Longus Muscle

Living crocodilians and limbed lepidosaurs have a large caudofemoralis longus muscle passing from tail to femur. Anatomical and electromyographic data support the conclusion that the caudofemoralis is the principal femoral retractor and thus serves as the primary propulsive muscle of the hind limb. Osteological evidence of both origin and insertion indicates that a substantial caudofemoralis longus was present in archosaurs primitively and was retained in the clades Dinosauria and Theropoda. Derived theropods (e.g., ornithomimids, deinonychosaurs, Archaeopteryx and birds) exhibit features that indicate a reduction in caudofemoral musculature, including fewer caudal vertebrae, diminished caudal transverse processes, distal specialization of the tail, and loss of the fourth trochanter. This trend culminates in ornithurine birds, which have greatly reduced tails and either have a minute caudofemoralis longus or lack the muscle entirely.As derived theropod dinosaurs, birds represent the best living model for reconstructing extinct nonavian theropods. Bipedal, digitigrade locomotion on fully erect limbs is an avian feature inherited from theropod ancestors. However, the primitive saurian mechanisms of balancing the body (with a large tail) and retracting the limb (with the caudofemoralis longus) were abandoned in the course of avian evolution. This strongly suggests that details of the orientation (subhorizontal femur) and movement (primarily knee flexion) of the hind limb in extant birds are more properly viewed as derived, uniquely avian conditions, rather than as retentions of an ancestral dinosaurian pattern. Although many characters often associated with extant birds appeared much earlier in theropod evolution, reconstructing the locomotion of all theropods as completely birdlike ignores a wealth of differences that characterize birds.

scholarly journals Partial lateral corpectomy associated with pediculectomy to treat extradural chondroma in a dog: technique description

2014 ◽  
Vol 66 (5) ◽  
pp. 1323-1328
Author(s):  
P.V.T. Marinho ◽  
C.C. Zani ◽  
P.C. Jark ◽  
B.W. Minto ◽  
M.T. Costa
Keyword(s):  
Spinal Cord ◽  
Surgical Technique ◽  
Poor Prognosis ◽  
Lumbar Vertebrae ◽  
Spinal Decompression ◽  
Cocker Spaniel ◽  
Hind Limbs

This study aimed to describe in detail the surgical technique of partial lateral corpectomy (PLC) associated with pediculectomy to treat an in vitroextradural chondroma. A 12-year old female Cocker Spaniel was seen in the hospital with proprioceptive ataxia of hind limbs associated with extradural compression between the 1st and 2nd lumbar vertebrae. The owner opted for euthanasia since the patient's condition changed due to simultaneous illnesses that culminated in a poor prognosis. The patient's body was formally ceded to perform experimental spinal decompression. The technique was effective to completely remove the epidural mass with minimal manipulation of the spinal cord.

Locomotion in Burrowing and Vagrant Wolf Spiders (Lycosidae)

1981 ◽  
Vol 92 (1) ◽  
pp. 305-321 ◽  
Author(s):  
T. M. WARD ◽  
W. F. HUMPHREYS
Keyword(s):  
Wolf Spider ◽  
The Body ◽  
Power Stroke ◽  
Phase Lag ◽  
Running Speed ◽  
Wolf Spiders ◽  
High Speeds ◽  
Phase Lags ◽  
The Relationship

Locomotion in the vagrant wolf spider Trochosa ruricola is compared to that in the burrow dwelling wolf spider Lycosa tarentula (Araneae: Lycosidae). L. tarentula takes relatively shorter steps than T. ruricola. At high speeds T. ruricola approximates an alternating tetrapod gait but this does not occur in L. tarentula. Phase lag differs between species and varies marginally with speed except for ipsilateral phase lags in L. tarentula which are erratic if they include leg 1. In both species the protraction/retraction ratio is directly related to both running speed and stepping frequency, but the relationship is more marked in L. tarentula. The protraction/retraction ratio is more variable in leg 1 and varies between legs along the body but by a greater amount in L. tarentula. In these spiders, in contrast to the situation in many insects, both the duration of protraction and retraction show marked inverse relationships to stepping frequency. The power stroke (retraction) occupies a variable proportion of the stepping cycle, which is not the case in other spiders, and this proportion is lower than for other spiders. It is suggested that the first pair of legs is used more for sensory than for locomotory purpose and that this is more marked in the burrow dwelling species, L. tarentula.

The locomotor system

2013 ◽  
Author(s):  
Martin E. Atkinson
Keyword(s):  
Vertebral Column ◽  
Cervical Vertebrae ◽  
Lumbar Vertebrae ◽  
Posterior Wall ◽  
Axial Skeleton ◽  
Intervertebral Discs ◽  
Central Canal ◽  
The Body ◽  
Thoracic Vertebrae ◽  
Locomotor System

The locomotor system comprises the skeleton, composed principally of bone and cartilage, the joints between them, and the muscles which move bones at joints. The skeleton forms a supporting framework for the body and provides the levers to which the muscles are attached to produce movement of parts of the body in relation to each other or movement of the body as a whole in relation to its environment. The skeleton also plays a crucial role in the protection of internal organs. The skeleton is shown in outline in Figure 2.1A. The skull, vertebral column, and ribs together constitute the axial skeleton. This forms, as its name implies, the axis of the body. The skull houses and protects the brain and the eyes and ears; the anatomy of the skull is absolutely fundamental to the understanding of the structure of the head and is covered in detail in Section 4. The vertebral column surrounds and protects the spinal cord which is enclosed in the spinal canal formed by a large central canal in each vertebra. The vertebral column is formed from 33 individual bones although some of these become fused together. The vertebral column and its component bones are shown from the side in Figure 2.1B. There are seven cervical vertebrae in the neck, twelve thoracic vertebrae in the posterior wall of the thorax, five lumbar vertebrae in the small of the back, five fused sacral vertebrae in the pelvis, and four coccygeal vertebrae—the vestigial remnants of a tail. Intervertebral discs separate individual vertebrae from each other and act as a cushion between the adjacent bones; the discs are absent from the fused sacral vertebrae. The cervical vertebrae are small and very mobile, allowing an extensive range of neck movements and hence changes in head position. The first two cervical vertebrae, the atlas and axis, have unusual shapes and specialized joints that allow nodding and shaking movements of the head on the neck. The thoracic vertebrae are relatively immobile. combination of thoracic vertebral column, ribs, and sternum form the thoracic cage that protects the thoracic organs, the heart, and lungs and is intimately involved in ventilation (breathing).

SKELETAL TRAUMA WITH IMPLICATIONS FOR INTRATAIL MOBILITY IN EDMONTOSAURUS ANNECTENS FROM A MONODOMINANT BONEBED, LANCE FORMATION (MAASTRICHTIAN), WYOMING USA

Palaios ◽  
2020 ◽  
Vol 35 (4) ◽  
pp. 201-214 ◽  
Author(s):  
BETHANIA C.T. SIVIERO ◽  
ELIZABETH REGA ◽  
WILLIAM K. HAYES ◽  
ALLEN M. COOPER ◽  
LEONARD R. BRAND ◽  
...  
Keyword(s):  
Traumatic Injury ◽  
Distal Region ◽  
High Impact ◽  
Body Region ◽  
Tail Region ◽  
Physical Trauma ◽  
Vertebral Centra ◽  
Gregarious Behavior ◽  
Caudal Vertebrae ◽  
Bone Abnormalities

ABSTRACT This study presents evidence of pre-mortem traumatic injury and its sequalae on multiple Edmontosaurus annectens skeletal elements recovered from a largely monodominant Cretaceous (Maastrichtian) bonebed. The sample consists of 3013 specimens excavated and prepared from two quarries, of which 96 elements manifest one or more macroscopic bone abnormalities and 55 specimens display pathology attributable to physical trauma. Evidence of traumatic pathology is strongly associated (P < .05) with body region, occurring disproportionately in the caudal vertebrae. Pre-mortem fractures with subsequent bone remodeling and hypertrophic ossification of caudal neural spines are present principally in the middle and mid-distal regions of the tail, while fractures of the vertebral centra are present primarily in the distal tail region. Other skeletal regions, such as chevrons, phalanges of the manus and ribs display unambiguous evidence of healed trauma, but with less frequency than the tail. These findings, in combination with current understanding of hadrosaurian tail biomechanics, indicate that intervertebral flexibility within the middle and mid-distal region of the tail likely rendered these caudal vertebrae more susceptible to the deleterious effects of repeated mechanical stress and subsequent trauma, potentially accompanying running locomotion and other high-impact herd interactions. Healed fractures within the region are also suggestive of accumulated injuries due to a combination of tail usage in defense and possibly accidental bumping/trampling associated with gregarious behavior.

THE EFFICACY OF DEXTRANS OF DIFFERENT MOLECULAR WEIGHTS IN SHOCK SECONDARY TO LIMB CLAMPING

1955 ◽  
Vol 33 (1) ◽  
pp. 553-561
Author(s):  
Lorraine C. Smith ◽  
R. E. Haist
Keyword(s):  
Intrinsic Viscosity ◽  
Fluid Therapy ◽  
Traumatic Shock ◽  
The Body ◽  
Plasma Expander ◽  
Molecular Weights ◽  
Hind Limbs ◽  
Removal Of Metal ◽  
Plasma Expanders

A degree of traumatic shock was produced in rats by the removal of metal clamps which had been applied to both hind limbs for a period of 10 hr. This was lethal within 24 hr. to all animals not receiving fluid therapy. The infusion of plasma expanders delayed or prevented the development of irreversible shock. All fluid therapy relieved the oliguria produced by the shock although this relief generally occurred 24 hr. after the release of the clamps. The plasma expander which best promoted survival was the Connaught dextran 13-1, a solution with an intrinsic viscosity of 0.34 (mean mol. wt. 150,000). Survival with the dextran solutions was increased with increasing molecular weights of the dextrans. This seemed to be related to the retention of the larger molecules for a longer period of time within the body.

Hydrodynamic drag of two frog species: Hymenochirus boettgeri and Rana pipiens

1987 ◽  
Vol 65 (5) ◽  
pp. 1085-1090 ◽  
Author(s):  
Julianna M. Gal ◽  
R. W. Blake
Keyword(s):  
Flow Visualization ◽  
Rana Pipiens ◽  
Swimming Performance ◽  
The Body ◽  
Hydrodynamic Drag ◽  
Subtraction Method ◽  
Flat Plates ◽  
Hind Limbs ◽  
Hymenochirus Boettgeri ◽  
Visualization Experiments

Drag of the aquatic frog Hymenochirus boettgeri was investigated by a series of drop-tank and flow visualization experiments. The maximum drag coefficient (CD) of the body and hind limbs was 0.24–0.11, for a Reynolds number (Re) of 1500–8000. Results of the flow visualization experiment support the CD values obtained for the body and hind limbs of H. boettgeri. CD similarly measured for Rana pipiens was 0.060–0.050, for a Re range of 16 600 – 40 400. A comparison of CD under dynamically similar conditions suggests that jumping may not compromise swimming performance in these two species. CD for the foot of H. boettgeri was examined by three methods: drop-tank experiments with isolated frog's feet and with isolated acetate model feet, and a subtraction method. CD for the isolated foot was 2.5–1.6 for 100 < Re < 700. Results were similar to those obtained with isolated model feet, where 1.8 > CD > 1.2 for 300 < Re < 1300. The subtraction method gave similar results to those obtained from drop-tank experiments with isolated model and real feet, within the Re range of 300–3000. The results of all three methods and flow visualization experiments support the assumption that animal paddles can be treated as three-dimensional flat plates, oriented normal to the direction of flow.

scholarly journals Muscular anatomy of the tail of the western grey kangaroo, Macropus fuliginosus

2014 ◽  
Vol 62 (2) ◽  
pp. 166 ◽  
Author(s):  
Rebekah Dawson ◽  
Nick Milne ◽  
Natalie M. Warburton
Keyword(s):  
Body Weight ◽  
The Body ◽  
Functional Roles ◽  
High Speeds ◽  
Hind Limbs ◽  
Grey Kangaroo ◽  
Western Grey Kangaroo ◽  
Low Speeds ◽  
Fifth Limb

The western grey kangaroo, Macropus fuliginosus, is a large-bodied kangaroo that engages in pentapedal locomotion at low speeds and bipedal hopping at high speeds. The tail is thought to have functional roles in both of these modes of locomotion. In pentapedal locomotion the tail acts as a ‘fifth limb’ to support the body weight together with the forelimbs while the hind limbs are drawn forward. The tail has also been suggested to have a role as a counterbalance during bipedal hopping. On the basis of these functional roles for the tail in locomotion, the caudal musculature of the western grey kangaroo was dissected and described in this study. The arrangement of the caudal musculature showed particular adaptations for the role of the tail in both pentapedal locomotion and bipedal hopping.

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