Andinodesma radicostata n. gen. n. sp., a grammysiid taxon from the Lower Devonian Catavi-Formation (Bolivia) and its autecological and phylogenetic implications

Andinodesma radicostata from the lowermost Devonian Cata vi Formation of Bolivia is a grammysiid genus, which is radially ribbed on the central parts of its valves and which exhibits a rather elongate anterior end. The umbones are placed near the middle of the valves and suggest an evolutionary state by Lower Devonian times, that rather parallels trends inGrammysia de Verneuil than in the morphologically closer relatedGrammysioidea Williams & Breger. Thus, the idea is supported, that not all taxa, beingGrammysia-shaped except for the conspicuous “cinctures” may easily be assigned toGrammysioidea. Living in an unstable shifting substratumA. radicostata evolved features that display a compromise between adaptation to free and relatively rapid burrowing and physical shell stabilization. The pattern of ornamentation suggests thatA. radicostata changed its mode of penetrating the sediment during one burrowing act. Anteriorly situated concentric ridges aided in more or less vertical down-probing during an initial phase of penetration whereas the radially ribbed central part of the valves indicates that rocking and forward movement predominated in later stages.     

Circadian pattern of plasma melatonin concentrations in the marmoset monkey (Callithrix jacchus)

This study describes the concentrations of melatonin in plasma samples taken from marmoset monkeys (Callithrix jacchus) every 4 h over three 24-h periods. A circadian pattern of secretion was apparent, with higher levels recorded at night (20.00–08.00 h) than during the day (08.00–20.00 h) and a peak concentration at 20.00 h. There was a significant difference in the mean day and night concentrations (32.5 ± 4.5 pg/ml versus 49.0 ± 6.9 pg/ml, respectively) with individual concentrations ranging between<10–60 pg/ml in the day and 15–200 pg/ml at night. Circadian plasma melatonin concentrations were similar over the three 24-h periods, in male (n = 3) and female (n = 3) monkeys, and in dominant (cyclic, n = 5) and subordinate (acyclic, n = 4) females. The results show a less pronounced circadian profile in the marmoset than is seen in the human but a similar profile to that in the seasonally breeding rhesus monkey.     

Radula und Fangarme beiMichelinoceras sp. aus dem Silur von Bolivien

New finds of michelinoceratid cephalopods from the Kirusillas-Shale (Ludlow/Silurian) of Ushpa-Ushpa in the Eastern Cordillera of the Bolivian Andes reveal parts of the radula and imprints of arms owing to extremely good preservation conditions. The imprints of soft parts point that the orthoce-rates had 10 arms, two of them shaped to long tentacles as recent coleoids have. Of more importance is the first proof of a michelinoceratid radula in situ. This is the first known ra-dula of lower palaeozoic cephalopods at all. TheMichelinoceras radula consisted of 7 teeth per row. So the radulae of michelinoceratid cephalopods are very similar to those of ammonites and coleoids. But there are great differences in the radula ofMichelinoceras sp. and that ofNautilus sp. All known radulae of fossil and recent cephalopods are compared and phylogenetic or systematic implications are discussed. The classification of the cephalopods into six subclasses as used in the “Treatise” turns out to be unnatural and should be given up. Finally ecological relations between the morphology of radula-elements and mode of life are dis-cussed. Size and number of radula teeth let suppose that thisMichelinoceras specimen must have been an adult individual living far off the coast in pelagic seas.