Abstracts from the 8th International Conference on cGMP Generators, Effectors and Therapeutic Implications

This work was supported by a restricted research grant of Bayer AG

Locomotory behaviour of early tetrapods from Blue Beach, Nova Scotia, revealed by novel microanatomical analysis

Evidence for terrestriality in early tetrapods is fundamentally contradictory. Fossil trackways attributed to early terrestrial tetrapods long predate the first body fossils from the Late Devonian. However, the Devonian body fossils demonstrate an obligatorily aquatic lifestyle. Complicating our understanding of the transition from water to land is a pronounced gap in the fossil record between the aquatic Devonian taxa and presumably terrestrial tetrapods from the later Early Carboniferous. Recent work suggests that an obligatorily aquatic habit persists much higher in the tetrapod tree than previously recognized. Here, we present independent microanatomical data of locomotor capability from the earliest Carboniferous of Blue Beach, Nova Scotia. The site preserves limb bones from taxa representative of Late Devonian to mid-Carboniferous faunas as well as a rich trackway record. Given that bone remodels in response to functional stresses including gravity and ground reaction forces, we analysed both the midshaft compactness profiles and trabecular anisotropy, the latter using a new whole bone approach. Our findings suggest that early tetrapods retained an aquatic lifestyle despite varied limb morphologies, prior to their emergence onto land. These results suggest that trackways attributed to early tetrapods be closely scrutinized for additional information regarding their creation conditions, and demand an expansion of sampling to better identify the first terrestrial tetrapods

A Diverse Tetrapod Fauna at the Base of 'Romer's Gap'.

The lack of fossil tetrapod bearing deposits in the earliest Carboniferous ('Romer's Gap') has provoked some recent discussions regarding the proximal cause, with three explanations being offered: environmental, taphonomic, and collection failure. One of the few, and earliest, windows into this time is the locality of Blue Beach exposed in the Tournaisian deposits at Horton Bluff lying along the Avon River near Hantsport, Nova Scotia, Canada. This locality has long been known but, because the fossils were deposited in high energy settings they are almost always disarticulated, so the fauna has not been described in detail. Recent intensive collection has revealed a diverse assemblage of material, including for the first time associated elements, which permits an evaluation of the faunal constituents at the locality. Although not diagnosable to a fine taxonomic level, sufficient apomorphies are present to identify representatives from numerous clades known from more complete specimens elsewhere. The evidence suggests a diverse fauna was present, including whatcheeriids and embolomeres. A single humerus previously had been attributed to a colosteid, but there is some uncertainty with this identification. Additional elements suggest the presence of taxa otherwise only known from the late Devonian. Depositional biases at the locality favor tetrapod fossils from larger individuals, but indirect evidence from trackways and tantalizing isolated bones evidences the presence of small taxa that remain to be discovered. The fossils from Blue Beach demonstrate that when windows into the fauna of 'Romer's Gap' are found a rich diversity of tetrapods will be shown to be present, contra arguments that suggested this hiatus in the fossil record was due to extrinsic factors such as atmospheric oxygen levels. They also show that the early tetrapod fauna is not easily divisible into Devonian and Carboniferous faunas, suggesting that some tetrapods passed through the end Devonian extinction event unaffected

On the intrinsic complexity of point finding in real singular hypersurfaces

In previous work we designed an efficient procedure that finds an algebraic sample point for each connected component of a smooth real complete intersection variety. This procedure exploits geometric properties of generic polar varieties and its complexity is intrinsic with respect to the problem. In the present paper we introduce a natural construction that allows to tackle the case of a non–smooth real hypersurface by means of a reduction to a smooth complete intersection

Humerus Types 2 and 3.

<p>YPM PU 20754, left humerus in A, dorsal; and B, ventral views, less areas still obscured by matrix. RM 20.6770 left? humerus in C, dorsal, and D, ventral, views. <b>Abbreviations</b>: <b>dp</b>, deltopectoral crest; <b>ect</b>, ectepicondyle; <b>ef</b>, entepicondylar foramen.</p

Femur Type 2 and tibia Type 1.

<p>NSM004GF045.034A-C, right and left femora (Type 2) and left tibia (Type 1) found in association. A-D, I, J, left femur in A, posterior, B, ventral, C, anterior, D, dorsal I, proximal, and J, distal views. E-H right femur in E, dorsal, F, anterior, G, ventral, and H, posterior views. Left tibia in K, flexor (ventral), and L, extensor (dorsal) views. <b>Abbreviations</b>: <b>ab</b>, adductor blade; <b>ac</b>, adductor crest; <b>cr</b>, thin anterior crest; <b>ff</b>, fibular facet; <b>fo</b>, fibular fossa; <b>ft</b>, fourth trochanter; <b>icf</b>, intercondylar fossa; <b>it</b>, internal trochanter; <b>itf</b>, intertrochanteric fossa; <b>tf</b>, tibial facet.</p

Pelvis Type 2.

<p>NSM014GF036.001, left ilium in medial view. <b>Abbreviations</b>: <b>ap</b>, anterior process; <b>pp</b>, posterior process; <b>rr</b>, robust ridge; <b>sac</b>, sacral rib facet.</p

Associated material from Blue Beach.

<p>NSM005GF045.034, the ‘Sherm Block’ (for collector Sherman Williams) of associated front and hind limb material.</p

Pelvis Type 1.

<p>NSM005GF045.001, right pelvis in A, medial, and B, lateral views. <b>Abbreviations</b>: <b>ap</b>, anterior process; <b>il</b>, ilium; <b>ish</b>, ischium; <b>ob</b>, obturator foramen; <b>pp</b>, posterior process; <b>pub</b>, pubis; <b>sac</b>, sacral rib facet.</p

Interclavicle.

<p>NSM.014.GF.036.005, undescribed interclavicle found in situ in the Theta Layer sandstone below the lighthouse in 2002. The morphology is consistent with a whatcheeriid and with similar elements from Dora, Scotland.</p