scholarly journals Stiffening in the carpus of Prosantorhinus germanicus (Perissodactyla, Rhinocerotidae) from Sandelzhausen (Germany)

PalZ ◽  
2021 ◽  
Author(s):  
Rico Schellhorn
Keyword(s):  
Sexual Dimorphism ◽  
Size Range ◽  
Carpal Bones ◽  
Mode Of Life ◽  
Carpal Joint ◽  
Both Bones

AbstractProsantorhinusgermanicus is a small, short-legged, teleoceratine rhino from the Miocene of Sandelzhausen (Bavaria, Germany). P.germanicus shows a high variation in some of its carpal bones. A unique modification of the articulation of Intermedium and Carpale 4 is described here. Special emphasis is given to additional articulation facets at the palmar processes of both bones. These additional contacts, working as stop facets, are unique among rhinos and restrict the flexion of the mid-carpal joint. Some individuals show these additional facets which prohibit the flexion within the wrist and therefore stiffen the carpus. Carpale 4 specimens without the additional facets show knob-like structures instead. These knobs are most likely precursory structures of those facets and the facets are fully developed in heavier males. A skeletal sexual dimorphism is not visible in the sample as all bones are in the same size range. The wrist stiffening in the mid-carpal joint supports a greater bodyweight and therefore could coincide with P.germanicus as a proposed dwarfed rhinoceros species. The stiffening can also be interpreted in favor of a semiaquatic mode of life. The stiffened carpus is more resistant against injuries while walking on muddy grounds in a wet environment.

Discerning the diets of sweep-feeding eurypterids: assessing the importance of prey size to survivorship across the Late Devonian mass extinction in a phylogenetic context

Paleobiology ◽  
2020 ◽  
pp. 1-13
Author(s):  
Emily S. Hughes ◽  
James C. Lamsdell
Keyword(s):  
Mass Extinction ◽  
Prey Species ◽  
Size Range ◽  
Prey Size ◽  
Phylogenetic Signal ◽  
Late Devonian ◽  
Evolutionary Trend ◽  
Average Spacing ◽  
Horseshoe Crabs ◽  
Mode Of Life

Abstract Eurypterids are generally considered to comprise a mixture of active nektonic to nektobenthic predators and benthic scavenger-predators exhibiting a mode of life similar to modern horseshoe crabs. However, two groups of benthic stylonurine eurypterids, the Stylonuroidea and Mycteropoidea, independently evolved modifications to the armature of their anterior appendages that have been considered adaptations toward a sweep-feeding life habit, and it has been suggested the evolution toward sweep-feeding may have permitted stylonurines to capture smaller prey species and may have been critical for the survival of mycteropoids during the Late Devonian mass extinction. There is a linear correlation between the average spacing of feeding structures and prey sizes among extant suspension feeders. Here, we extrapolate this relationship to sweep-feeding eurypterids in order to estimate the range of prey sizes that they could capture and examine prey size in a phylogenetic context to determine what role prey size played in determining survivorship during the Late Devonian. The mycteropoid Cyrtoctenus was the most specialized sweep-feeder, with comblike appendage armature capable of capturing mesoplankton out of suspension, while the majority of stylonurines possess armature corresponding to a prey size range of 1.6–52 mm, suggesting they were suited for capturing small benthic macroinvertebrates such as crustaceans, mollusks, and wormlike organisms. There is no clear phylogenetic signal to prey size distribution and no evolutionary trend toward decreasing prey sizes among Stylonurina. Rather than prey size, species survivorship during the Late Devonian was likely mediated by geographic distribution and ability to capitalize on the expanding freshwater benthos.

Radiographic assessment of the equine carpal joint under incremental loads and during flexion

2019 ◽  
Vol 15 (5) ◽  
pp. 359-370 ◽  
Author(s):  
T.A.O. Olusa ◽  
C.M. Murray ◽  
H.M.S. Davies
Keyword(s):  
Carpal Bones ◽  
Carpal Bone ◽  
Confined Space ◽  
Radiographic Assessment ◽  
Ligament Rupture ◽  
The Press ◽  
Carpal Joint ◽  
Commercial Press ◽  
Radiographic Changes ◽  
Osteochondral Fractures

Non-physiologic loading of the carpal bones is believed to result in osteochondral fractures, ligament rupture and axial instability in the equine forelimb; however, the mechanism of carpal damage due to non-physiologic loading of the carpus is largely unknown. To investigate carpal stability (alignment and direction of carpal bones’ movement) under load and during flexion, some previously described carpal parameters were measured on radiographs obtained from 24 equine cadaver limbs (aged 10.71±4.15 years). The limbs were transected at the antebrachial midshaft, axially loaded in a commercial press and serially radiographed under a range of incremental loads (extension) and 2 flexion positions. The extensions were measured by a 10° decrease in the dorsal fetlock angle (DFA) from 160° to 110° (DFA160 to DFA110) using the jacking system of the press; and flexions at palmar carpal angle of 45° and 90° (PCA45 and PCA90). As loading increased from DFA160 to DFA110 there was a progressive significant increase in Third Carpal bone Palmar Facet Angle (C3PalFCA: 86.46±2.54° to 88.60±2.51°) but a decrease in Dorsal Carpal Angle (DCA: 173.03±3.47° to 159.65±4.09°); Medial Carpal Angle (MCA: 186.31±1.90° to 184.61±2.26°); and Groove width of the Cr-Ci intercarpal ligament (GW.Cr-Ci ICL: 9.35±1.20° to 8.83±1.13°) while no significant differences were observed for Distal Radial Slope Carpal Angle (DRSCA) and Intermediate carpal bone Proximal Tuberosity-Radial Angle (CiPxTRA). A generalised medio-distal directional displacement in the carpal bones’ movement were observed. In conclusion, increased load on the forelimb (carpus) produced carpal hyperextension with measurable radiographic changes in the position and alignment of the carpal bones. The non-stretching (strain) or shortening of the Cr-Ci ICL during loading, indicated by the decrease in GW.Cr-Ci ICL, suggests a relaxed intercarpal ligament within a confined space which appears to absorb compressional load transferred from carpal bones and redistribution of concussion forces within the carpal joint during loading thereby providing a useful mechanism to minimise carpal damage.

Studies on Insects bred from Barley, Wheat, Maize and Oats

1942 ◽  
Vol 32 (4) ◽  
pp. 309-325 ◽  
Author(s):  
F. D. Goodliffe
Keyword(s):  
Sexual Dimorphism ◽  
Winter Wheat ◽  
Size Range ◽  
Flea Beetle ◽  
Wheat Crop ◽  
Potted Plants ◽  
Flea Beetles ◽  
Large Numbers ◽  
Winter Wheat Crop ◽  
Wet Weather

Larvae of a flea-beetle, Chaetocnema arida, were found mining in the stems of young barley shoots in June 1939.Chlorops pumilionis larvae infested barley most heavily in fields where Agriotes larvae were doing most damage. The Chlorops adults showed marked sexual dimorphism in both size and colour. The size range for this species is correlated with a proportionate size range in its parasites Coelinius niger and Stenomalus micans. Perforations 1·3 mm. in diameter in the top of a cage were sufficient for the escape of Stenomalus but not of Chlorops or Coelinius.Lasiosina cinctipes larvae were commonly synoecious with Chlorops in barley shoots, but in some cases (5–10 per cent.) they were living without Chlorops. In these shoots the nodes were not swollen as in Chlorops infestation. Lasiosina was not attacked by the above parasites of Chlorops.The larvae of Elachiptera cornuta infested shoots already badly damaged by other species and were accompanied by many Lasiosina larvae. Wet weather in July favours these two species. Their puparia differ in the form of the posterior spiracles. Elachiptera also occurred in maize and wheat.Meromyza saltatrix var. nigriventris was present in stunted barley shoots in small numbers, producing swelling of the nodes very like that due to Chlorops. The summer pigmentation in both these species in Hampshire differed from that reported by Mesnil in France. Meromyza was also bred from wheat. Meromyza puparia, unlike those of Chlorops, were attached to barley sheathing-leaves by silk.Oscinella frit larvae, infesting young sweet maize shoots at Gosden, Surrey, were either accompanied or followed by those of Aphanotrigonum trilineatum and Elachiptera. Infesting oat shoots at Long Sutton, Hampshire, Oscinella frit larvae were accompanied by larvae of Lasiosina and Camarota curvinervis. Adults of the latter emerged from stunted barley shoots in September. They showed some resemblance to flea beetles, possibly protective. Oscinella frit was also bred in small numbers from stunted wheat and barley shoots. The Chalcid, Callitula pyrrhogaster, was reared from pupae of this species found in oat shoots.Larvae of a Muscid, Hylemyia (Phorbia) genitalis, infested a winter wheat crop in large numbers in May 1940. Tropidoscinis albipalpis, Oscinella? gracilior and Agromyza nigripes, were bred in small numbers from potted plants of this crop kept in a cage in the laboratory during the summer. Hylemyia genitalis and Agromyza (Domomyza) ambigua pupated in the soil surrounding the roots of these plants. The adults (together with a Braconxd parasite, Phaenocarpa pullata, Hal.) emerged from the soil in the following spring.

Partial Carpal Arthrodesis in the Horse

1990 ◽  
Vol 03 (02) ◽  
pp. 51-60 ◽  
Author(s):  
J. R. Taylor ◽  
R. D. Welch ◽  
J. B. Stricklin ◽  
J. A. Auer ◽  
J. P. Watkins
Keyword(s):  
Internal Fixation ◽  
Dynamic Compression ◽  
Joint Capsule ◽  
Carpal Bones ◽  
Carpal Bone ◽  
Collateral Ligaments ◽  
Carpal Joint ◽  
Comminuted Fractures

SummaryOver a period of 6 years, four horses and two foals were treated with partial carpal arthrodesis. The problems treated included one luxation each of the carpometacarpal, and the antebrachiocarpal joint, as well as one subluxation of the carpometacarpal and the middle carpal joints. The luxations developed secondary to rupture of the joint capsule as well as one or two collateral ligaments. In three cases, comminuted fractures of the distal row of carpal bones, complicated in one of these cases by a fracture of the intermediate carpal bone, were treated. Arthrodesis by internal fixation using T-plates or dynamic compression plates of various sizes was successful in salvaging some of the animals. The various cases are discussed in detail as to technique and reason of its application. One horse was euthanatized, two are presently used for pleasure riding and three horses are used for breeding purposes. The horses treated by means of arthrodesis were compared to one case of luxation of the middle carpal joint, which was treated unsuccessfully by external coaptation alone.The results of partial carpal arthrodesis in four horses and two foals are described, as are the techniques employed and the results.

Sexual dimorphism and predaceous feeding habits of the waterstrider Gerris remigis Say (Heteroptera: Gerridae)

1990 ◽  
Vol 68 (12) ◽  
pp. 2688-2691 ◽  
Author(s):  
Edward B. McLean
Keyword(s):  
Sexual Dimorphism ◽  
Size Range ◽  
Feeding Habits ◽  
Potential Prey ◽  
Body Width ◽  
Size Dependent ◽  
Median Size ◽  
Terrestrial Insects ◽  
Prey Items ◽  
Surface Drift

The feeding habits of Gerris remigis were examined in a southeastern Ontario stream. Gerrids with prey items were collected from two pools along a 15-m length of the site. The size distribution of potential prey available in the surface drift during the survey was estimated. Gerrid prey consisted mainly of terrestrial insects; coleopterans, dipterans, homopterans, and hymenopterans represented the predominant orders. The median size of prey taken by all gerrids was significantly larger than that available in the surface drift. A sexual dimorphism in gerrid body size was found. The length of prey taken did not differ between the sexes; however, the diet of the larger bodied females consisted of prey with a greater median body width than the diet of smaller males. Females also took a greater size range of prey. These results support a size-dependent predation model which predicts that the upper size range of prey that can be successfully captured is correlated with predator size.

Microtomy of spherical Al2O3 powders

1983 ◽  
Vol 41 ◽  
pp. 74-75
Author(s):  
E.J. Jenkins ◽  
D.S. Tucker ◽  
J.J. Hren
Keyword(s):  
Thin Film ◽  
Size Range ◽  
Particle Aggregation ◽  
Ion Milling ◽  
Thin Sections ◽  
Α Phase ◽  
Convenient Means ◽  
Van Der Waals Attraction ◽  
Negative Feature ◽  
Film Substrate

The size range of mineral and ceramic particles of one to a few microns is awkward to prepare for examination by TEM. Electrons can be transmitted through smaller particles directly and larger particles can be thinned by crushing and dispersion onto a substrate or by embedding in a film followed by ion milling. Attempts at dispersion onto a thin film substrate often result in particle aggregation by van der Waals attraction. In the present work we studied 1-10 μm diameter Al2O3 spheres which were transformed from the amprphous state to the stable α phase.After the appropriate heat treatment, the spherical powders were embedded in as high a density as practicable in a hard EPON, and then microtomed into thin sections. There are several advantages to this method. Obviously, this is a rapid and convenient means to study the microstructure of serial slices. EDS, ELS, and diffraction studies are also considerably more informative. Furthermore, confidence in sampling reliability is considerably enhanced. The major negative feature is some distortion of the microstructure inherent to the microtoming operation; however, this appears to have been surprisingly small. The details of the method and some typical results follow.

Microdiffraction Patterns of Small Metallic Particles II; Theoretical Analysis

1982 ◽  
Vol 40 ◽  
pp. 668-669
Author(s):  
A. Gómez ◽  
P. Schabes-Retchkiman ◽  
M. José-Yacamán ◽  
T. Ocaña
Keyword(s):  
Experimental Data ◽  
Electron Diffraction ◽  
Theoretical Analysis ◽  
Size Range ◽  
Dynamical Theory ◽  
Metallic Particles ◽  
Splitting Effect

The splitting effect that is observed in microdiffraction pat-terns of small metallic particles in the size range 50-500 Å can be understood using the dynamical theory of electron diffraction for the case of a crystal containing a finite wedge. For the experimental data we refer to part I of this work in these proceedings.

Electron Microscopy of the Shape of Small Metal Particles

1977 ◽  
Vol 35 ◽  
pp. 300-301
Author(s):  
M. Jose Yacaman
Keyword(s):  
Electron Microscopy ◽  
Metal Particle ◽  
Field Experiments ◽  
Size Range ◽  
Dark Field ◽  
Metal Particles ◽  
Bragg Condition ◽  
Crystal Particle ◽  
Small Metal Particle ◽  
Small Metal Particles

In the Study of small metal particles the shape is a very Important parameter. Using electron microscopy Ino and Owaga(l) have studied the shape of twinned particles of gold. In that work electron diffraction and contrast (dark field) experiments were used to produce models of a crystal particle. In this work we report a method which can give direct information about the shape of an small metal particle in the amstrong- size range with high resolution. The diffraction pattern of a sample containing small metal particles contains in general several systematic and non- systematic reflections and a two-beam condition can not be used in practice. However a N-beam condition produces a reduced extinction distance. On the other hand if a beam is out of the bragg condition the effective extinction distance is even more reduced.

Freeze-dried dispersions for automated SEM analysis of individual submicron airborne particulates

1992 ◽  
Vol 50 (1) ◽  
pp. 408-409
Author(s):  
Karen A. Katrinak ◽  
David W. Brekke ◽  
John P. Hurley
Keyword(s):  
Air Pollutants ◽  
Size Range ◽  
Sem Analysis ◽  
Individual Particle ◽  
Chemical Data ◽  
Particle Analysis ◽  
Bulk Analysis ◽  
Airborne Particulates ◽  
Freeze Dried ◽  
Individual Particle Analysis

Individual-particle analysis is well established as an alternative to bulk analysis of airborne particulates. It yields size and chemical data on a particle-by-particle basis, information that is critical in predicting the behavior of air pollutants. Individual-particle analysis is especially important for particles with diameter < 1 μm, because particles in this size range have a disproportionately large effect on atmospheric visibility and health.

Electron Microscopy in the Study of Natural Phytoplankton Assemblages

1985 ◽  
Vol 43 ◽  
pp. 620-623
Author(s):  
Linda Sicko-Goad
Keyword(s):  
Electron Microscopy ◽  
Aquatic Environment ◽  
Size Range ◽  
Physical Parameters ◽  
Specific Information ◽  
Phytoplankton Assemblages ◽  
Phytoplankton Productivity ◽  
Ecosystem Effects ◽  
Time Of Year ◽  
Species Specific

Although the use of electron microscopy and its varied methodologies is not usually associated with ecological studies, the types of species specific information that can be generated by these techniques are often quite useful in predicting long-term ecosystem effects. The utility of these techniques is especially apparent when one considers both the size range of particles found in the aquatic environment and the complexity of the phytoplankton assemblages.The size range and character of organisms found in the aquatic environment are dependent upon a variety of physical parameters that include sampling depth, location, and time of year. In the winter months, all the Laurentian Great Lakes are uniformly mixed and homothermous in the range of 1.1 to 1.7°C. During this time phytoplankton productivity is quite low.

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