A new near-shore marine fauna and flora from the early neogene of northwestern Venezuela
america; extinction; Paleontology; veneridae
A diverse near-shore marine fauna existed during the early Miocene in what is today an arid inland region about 90 km south of the Caribbean coast of northern Venezuela, a poorly known area geologically and paleontologically. The fossil locality consists of more than 100 m of section exposed in an area of about 1 km(2). We report the discovery of 20 molluscan species, one crab (Portunus oblongus), at least three shades (Hemipristis serra and Carcharhinus spp.), one turtle ("Podocnemis" venezuelensis), one crocodile (Crocodylidae), two whales (Odontoceti) and a three dimensional cast of the mesocarp or endocarp of a palm fruit. Several taxa are reported for the first time in Venezuela or in northern South America. The fauna indicates, or at least is consistent with, an early Miocene age for the locality, and a near-shore and shallow water marine depositional environment. We suggest that the earliest mammal previously reported from Venezuela, the pyrothere Proticia venezuelensis, was collected in Miocene rocks of the Castillo Formation instead of Eocene rocks of the Trujillo Formation.
Sanchez-Villagra M R; Burnham R J; Campbell D C; Feldmann R M; Gaffney E S; Kay R F; Lozsan R; Purdy R; Thewissen J G M
Journal of Paleontology
2000
2000-09
Journal Article
<a href="http://doi.org/10.1666/0022-3360(2000)074%3C0957:annsmf%3E2.0.co;2" target="_blank" rel="noreferrer noopener">10.1666/0022-3360(2000)074%3C0957:annsmf%3E2.0.co;2</a>
Hyperdisease in the late Pleistocene: validation of an early 20th century hypothesis
arthritis; Bison; erosive disease; extinction; hyperdisease; infection; lesions; mastodon; Pleistocene; Science & Technology - Other Topics; tuberculosis
The hypothesis of disease-related large mammal extinction has new support. A unique pathologic zone of resorption was first noticed in a Hiscock Mammut americanum metacarpal. The pathognomonic zone of resorption was present in fifty-nine (52%) of 113 skeletons with feet available for examination. Metacarpals and metatarsals were most commonly affected. Associated rib periosteal reaction is highly suggestive of tuberculosis and the foot lesions were identical to that documented in Bison as pathognomonic for tuberculosis. Recognizing that only a portion of animals infected by infectious tuberculosis develop bone involvement, the high frequency of the pathology in M. americanum suggests that tuberculosis was not simply endemic, but actually pandemic, a hyperdisease. Pandemic tuberculosis was one of several probable factors contributing to mastodon extinction.tinction.
Rothschild B M; Laub R
Naturwissenschaften
2006
2006-11
Journal Article
<a href="http://doi.org/10.1007/s00114-006-0144-8" target="_blank" rel="noreferrer noopener">10.1007/s00114-006-0144-8</a>
Why are some species more commonly afflicted by arthritis than others? A comparative study of spondyloarthropathy in primates and carnivores
ankylosing spondylitis; arthritis; body size; carnivores; comparative study; disease; disease risk; Environmental Sciences & Ecology; Evolutionary Biology; extinction; Genetics &; gorilla-gorilla; group-size; Heredity; inflammatory arthritis; IUCN threat status; joint; museum specimens; population-density; primates; reactive arthritis; rheumatoid-arthritis; risk; spondyloarthropathy
Spondyloarthropathy is a painful arthritic affliction of humans that also occurs in wild mammals. Important questions remain concerning the underlying causes of spondyloarthropathy in mammals, particularly regarding whether it is infectious in origin or driven by genetic predisposition and environmental stressors. Moreover, spondyloarthropathy has negative effects on host fitness, leading to potential conservation concerns if it impacts threatened species. Using a comparative data set on the prevalence of joint disease in 34 primate species and 100 carnivore species, we tested predictions involving the epidemiological correlates of spondyloarthropathy in wild mammals. Analyses revealed that 5.6% of primates and 3.6% of carnivores exhibited signs of spondyloarthropathy, with maximum incidence as high as 22% in great apes and 27% in bears. We tested whether prevalence of spondyloarthropathy increases with population density and group size, greater contact with soil, a slower host life history, increased ranging, dietary factors and body mass. We found general support for an effect of body mass, with larger bodied primates and carnivores exhibiting a higher prevalence of spondyloarthropathy. In addition, more threatened species experienced higher rates of spondyloarthropathy, with this association influenced by body mass and phylogeny. The effect of body mass could reflect that larger animals are exposed to more pathogens through greater consumption of resources, or that joints of larger bodied mammals experience greater biomechanical stresses, resulting in inflammation and activation of local joint infections.
Nunn C L; Rothschild B; Gittleman J L
Journal of Evolutionary Biology
2007
2007-03
Journal Article
<a href="http://doi.org/10.1111/j.1420-9101.2006.01276.x" target="_blank" rel="noreferrer noopener">10.1111/j.1420-9101.2006.01276.x</a>
Lesions of the basolateral amygdala abolish the ability of drug associated cues to reinstate responding during withdrawal from self-administered cocaine.
Amygdala/*physiopathology; Animals; Association Learning/*physiology; Brain Mapping; Cerebral/*physiology; Classical/physiology; Cocaine-Related Disorders/*physiopathology; Conditioning; Dominance; Dopamine/physiology; Extinction; Male; Motivation; Psychological/physiology; Rats; Reinforcement Schedule; Self Administration; Sprague-Dawley; Substance Withdrawal Syndrome/*physiopathology
This study investigated the ability of bilateral excitotoxic lesions of the basolateral amygdala (BLA) to disrupt cocaine self-administration, responding during extinction sessions, and stimulus cued recovery of extinguished responding in rats. BLA and sham lesions following 7 days of 3 h limited access cocaine self-administration sessions (0.33 mg/infusion) on a fixed ratio 1 (FR1) schedule of reinforcement failed to alter cocaine intake and responding on 7 subsequent days of self-administration. This lack of effect suggests that the BLA is not paramount for the maintenance of cocaine's reinforcing effects. In contrast, BLA lesions, but not sham lesions, following 7 to 14 days of cocaine self-administration attenuated responding on a lever associated with cocaine infusions on the first day of extinction sessions and blocked the ability of drug associated stimuli to reinstate extinguished responding following 20 daily extinction sessions. However, lesions of the BLA did not attenuate stimulus cued recovery of responding following 43 days of withdrawal. These results are consistent with the hypothesis that the BLA is important for the conditioned incentive properties of reinforcers, but not primary reinforcement itself.
Meil W M; See R E
Behavioural brain research
1997
1997-09
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1016/s0166-4328(96)02270-x" target="_blank" rel="noreferrer noopener">10.1016/s0166-4328(96)02270-x</a>
Extinction of cocaine-induced place approach in rats: a validation of the "biased" conditioning procedure.
Animals; Classical; Cocaine/*pharmacology; Conditioning; Extinction; Habituation; Inbred Strains; Male; Operant/*drug effects; Psychological/*drug effects; Psychophysiologic/drug effects; Rats; Reward
It has often been demonstrated that when a rat is conditioned in a cue-specific environment that has been repeatedly paired with cocaine injections, it will spend more time in that environment than it does in a saline-paired environment. This behavioral procedure is commonly known as the conditioned place preference (CPP)-test. At present, a firm theoretical understanding of the mechanisms underlying the production of a CPP are unknown. It is insufficient merely to know that a CPP can result after repeated drug pairings. Rather, it is necessary that the procedure is validated within a learning theory framework. The objective of the present study was, therefore, to establish that what is observed in place preference studies was, indeed, conditioning. This was accomplished by determining whether a cocaine-induced increase in time spent in a drug-paired environment was subject to attenuation following extinction trials. Rats were tested for their initial bias in spending more time in one of two stimulus-specific chambers of a place-conditioning apparatus. On four occasions, rats were injected with 2.5 mg/kg cocaine and confined to their less-preferred chamber whereas, on four alternating sessions, they were conditioned with saline (vehicle) in their preferred chamber. Subsequent testing in the nondrugged state revealed that these rats displayed a significant increase in the time spent in their initially least-preferred environment compared to baseline measurements. Following establishment of this cocaine-induced CPP, the rats were injected only with saline and conditioned for an equal number of sessions (i.e., four).(ABSTRACT TRUNCATED AT 250 WORDS)
Calcagnetti D J; Schechter M D
Brain research bulletin
1993
1905-06
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1016/0361-9230(93)90102-h" target="_blank" rel="noreferrer noopener">10.1016/0361-9230(93)90102-h</a>