NOTES ON NESTING AND GREGARIOUS BEHAVIOR OF A BLUE NEST-RENTING WASP, CHALYBION JAPONICUM (GRIBODO) WITH COMMENTS ON COMMONLY USED NAME FOR CHALYBION SPECIES (HYMENOPTERA: SPHECIDAE)

Humans and other group-living animals tend to distribute their social effort disproportionately. Individuals predominantly interact with a small number of close companions while maintaining weaker social bonds with less familiar group members. By incorporating this behavior into a mathematical model, we find that a single parameter, which we refer to as social fluidity, controls the rate of social mixing within the group. Large values of social fluidity correspond to gregarious behavior, whereas small values signify the existence of persistent bonds between individuals. We compare the social fluidity of 13 species by applying the model to empirical human and animal social interaction data. To investigate how social behavior influences the likelihood of an epidemic outbreak, we derive an analytical expression of the relationship between social fluidity and the basic reproductive number of an infectious disease. For species that form more stable social bonds, the model describes frequency-dependent transmission that is sensitive to changes in social fluidity. As social fluidity increases, animal-disease systems become increasingly density-dependent. Finally, we demonstrate that social fluidity is a stronger predictor of disease outcomes than both group size and connectivity, and it provides an integrated framework for both density-dependent and frequency-dependent transmission.

Download Full-text

New insights into the lifestyle of Allosaurus (Dinosauria: Theropoda) based on another specimen with multiple pathologies

10.7287/peerj.preprints.824v1 ◽

2015 ◽

Author(s):

Christian Foth ◽

Serjoscha Evers ◽

Ben Pabst ◽

Octávio Mateus ◽

Alexander Flisch ◽

...

Keyword(s):

Traumatic Event ◽

Cervical Vertebrae ◽

Cervical Vertebra ◽

Morrison Formation ◽

Gregarious Behavior ◽

Lower Jaw ◽

Successful Prevention ◽

Left Humerus ◽

Left Scapula

Adult large-bodied theropods are often found with numerous pathologies. A large, almost complete, probably adult Allosaurus specimen from the Howe Stephens Quarry, Morrison Formation (Late Kimmeridgian–Early Tithonian), Wyoming, shows multiple pathologies. Pathologic bones include the left dentary, two cervical vertebrae, one cervical and several dorsal ribs, the left scapula, the left humerus, right ischium, and two left pedal phalanges. These pathologies can be classified as follows: the fifth cervical vertebra, the scapula, several ribs and the ischium are traumatic, and a callus on the shaft of the left pedal phalanx II-2 is traumatic-infectious. Traumatically fractured elements exposed to frequent movement (e.g. the scapula and the ribs) show a tendency to develop pseudarthroses instead of callus healing. The pathologies in the lower jaw and a reduced flexor tubercle of the left pedal phalanx II-2 are most likely traumatic or developmental in origin. The pathologies on the fourth cervical are most likely developmental in origin or idiopathic, that on the left humerus is infectious or idiopathic, whereas left pedal phalanx IV-1 is classified as idiopathic. With exception of the ischium, all traumatic / traumatic-infectious pathologic elements show unambiguous evidences of healing, indicating that the respective pathologies did not cause the death of this individual. Alignment of the scapula and rib pathologies from the left side suggests that all may have been caused by a single traumatic event. The ischial fracture may have been fatal. The occurrence of multiple traumatic pathologies again underlines that large-bodied theropods experienced frequent injuries during life, indicating an active predatory lifestyle, and their survival perhaps supports a gregarious behavior for Allosaurus. Signs of infections are scarce and locally restricted, indicating a successful prevention of the spread of pathogens, as it is the case in extant reptiles (including birds).

Download Full-text

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

Palaios ◽

10.2110/palo.2019.079 ◽

2020 ◽

Vol 35 (4) ◽

pp. 201-214 ◽

Cited By ~ 1

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.

Download Full-text