External Mould Research Articles

A conundrum from the Llandovery (Lower Silurian) of Devil’s Dingle, Shropshire

Summary A root-like structure from the Llandovery (Telychian) of Devil’s Dingle, Shropshire, may be an invertebrate attachment structure or a trace fossil close to Chondrites isp. von Sternberg, although the possibility that it is a Recent plant root trace is also considered. The specimen is preserved as an external mould in a medium-grained sandstone bed, oriented perpendicular to bedding on a joint surface. The structure has a central shaft that is inflated at branching points; lateral branches are directed sub-horizontally at shallower depths and at progressively greater angles to the horizontal in deeper parts of the structure. Multiple branches are regularly distributed down the shaft. With insufficient definitive features to determine whether it is a body or, more probably, a trace fossil, the specimen is named, conservatively, as Chondrites ? sp., although a Recent botanical origin is not discounted.

Campanile trevorjacksonisp. nov. (Mollusca: Gastropoda) from the Eocene of Jamaica: at last, a name for the first fossil used in intercontinental biostratigraphic correlation (de la Beche 1827)

AbstractA new species of giant fossil gastropod belonging to the genusCampanile,Campanile trevorjacksonisp. nov., is described from the Lower Eocene Stettin Formation of the Yellow Limestone Group of Jamaica. Over 180 years ago, internal moulds of these giant gastropods were first reported from the Eocene of Jamaica and referred to asCerithium; it is only with the discovery of an external mould of the shell spire that it can now be removed from open nomenclature. The ornate shell ofC. trevorjacksonihas flat‐sided to slightly rounded whorls; straight, impressed sutures; seven beaded, spiral cords per whorl and a nodose subsutural ridge in the more adapertural part of the shell. This sculpture differentiatesC. trevorjacksonifrom other PaleogeneCampanilespecies. In 1827, de la Beche includedC. trevorjacksoni(asCerithium) in a list of over 20 taxa with which he correlated his white limestone formation (including the Yellow Limestone Group of modern use) with the (Eocene)Calcaire grossierof the Paris Basin. These specimens are lost, but re‐examination of de la Beche's list suggests his identifications were mostly reasonable. Copyright © 2008 John Wiley & Sons, Ltd.

SOLNHOFEN-STYLE SOFT-TISSUE PRESERVATION IN A NEW SPECIES OF TURTLE FROM THE CRATO FORMATION (EARLY CRETACEOUS, APTIAN) OF NORTH-EAST BRAZIL

The partial, articulated skeleton of a pleuro- diran turtle from the Nova Olinda Member of the Crato Formation (Araripe Basin) of north-east Brazil displays an impression of the outline of the soft tissues surrounding the left hind limb. The external mould of the soft tissue surface preserves only the gross morphology of the limb although the outline of the limb is well defined. It appears to be an external mould of the limb's surface, which formed prior to the decay of the integument. The limb skeleton is mostly fully articulated. This style of preserva- tion is comparable with the mouldic preservation found in such famous fossils as the feathered Archaeopteryx speci- mens of the Solnhofen limestone. Although soft-tissue pre- servation is occasionally encountered in the Crato Formation, this is the first documented occurrence of mouldic preservation of body outline reported for this Konservat-Lagerstatten. The new specimen is referred to the pelomedusoid Araripemys and represents a new species, A. arturi sp. nov., which is described here.

First record of Pachydiscus noetlingi Kennedy, 1999 (Ammonoidea) from the Maastrichtian type area (the Netherlands)

AbstractTwo specimens of a pachydiscid ammonite, a fragmentary silicified phragmocone from the Kunrade Limestone facies at Kunrade (Schunck), and a partial external mould preserved in flint from the Nekum Member (both Maastricht Formation, Belemnitella junior Zone of authors) at the former Blom quarry (Berg en Terblijt), are identified as Pachydiscus (P.) noetlingi Kennedy, 1999, a species previously known only from the Upper Maastrichtian of Baluchistan (Pakistan). This new record underscores the proposal of incursions of Tethyan biota into the type area of the Maastrichtian Stage, previously documented for other groups, including echinoderms and bivalves, as well.

An addition to the graptolite fauna from the Superstes Mudstone Formation, Girvan district

In a recent paper I figured some examples of the graptolite Dicellograptus alabamensis Ruedemann, 1908, from the Superstes Mudstone Formation in the Girvan cover-sequence, and used that species to support the inference that the formation lies in the lower part of the gracilis graptolite zone (Rushton 2001, p. 49, fig. 2b–g). However, one figured specimen (Rushton 2001, fig. 2b) appears to have been incorrectly identified, and should rather be referred to Dicranograptus irregularis Hadding, 1913. The outline of the specimen in question, British Geological Survey GSE 8213 (Fig. la), shows what appears to be a short biserial portion with two pairs of thecae. Unlike the best preserved of the graptolites from the Superstes Mudstone, it is strongly flattened and has lost much of the periderm, so that the critical median part of the proximal end is preserved only as an external mould; as the specimen was associated with several specimens of Dicellograptus alabamensis, and has similar dimensions and thecal form, I made the assumption that the specimen was a D. alabamensis in which the spiral form of the rhabdosome had allowed the proximal parts of the stipes to become flattened with one on top of the other. I had briefly considered the possibility that it was a Dicranograptus, and compared it with the smallest species known to me, D. irregularis Hadding, as revised by Hughes (1989, text-fig. 20a and b), but rejected identification with that species because the specimen from the Superstes Mudstone seemed significantly smaller. Further consideration has . . . I thank Dr. M. Howe for access to specimens in the collections of the British Geological Survey, and Mr. G. R. Ganis and Dr. Mark Williams for discussion.

Hyolith guts in the Cambrian of northern Australia ‐turning hyolithomorphs upside down

A single specimen of the early Middle Cambrian (Ordian) orthothecimorph hyolith Gudugu-wan hardmani with preserved gut filling has been discovered in the Montejinni Limestone, Wiso Basin, northern Australia. This represents only the eighth such occurrence worldwide. The specimen is unique among orthothecimorphs in retaining the gut filling in combination with the external mould of the operculum and invites revision of the accepted soft-part recon struction in this group, whereby the opercular lateral processes are now recognized to be ventral. Thus orthothecimorph conchs, if horizontal in life, would have been oriented ventral side down, while hyolithomorphs adopted the reverse orientation: horizontal, ventral side up.

A Cretaceous hermit crab from Antarctica: predatory activities and bryozoan symbiosis

A hermit crab assigned to Paguristes sp. is described from James Ross Island, Antarctica. The fossil was obtained from the Gamma Member of the Santa Marta Formation of late Campanian age. The specimen is associated with an external mould of the gastropod Taioma, that was encrusted by a colony of ascophoran bryozoans. Another specimen of Taioma shows typical predatory marks in the outer lip that are attributed to the action of pagurids. It is concluded that the particular dwelling habits of the hermit crabs, their symbiosis with bryozoan, and their predatory activities were already established by the end of the Cretaceous.

Lost & Found: 207. Lotagnostus trisectus (Salter 1864) and the Tennant collection

Adrian Rushton (British Geological Survey, Keyworth, Notts. NG12 5GG) is seeking the two syntype specimens of the trilobite Lotagnostus trisectus (Salter, 1864) from the Upper Lingula Flags of Whiteleaved Oak, Malvern, described as Agnostus trisectus by Salter (1864, pl.l, fig.11, p.10; reproduced as Fig.2 here). Salter mentioned two specimens 'sent to Mr Tennant' who lent them to Salter. The Survey have a sealing-wax cast of the figured specimen (GSM 8768), 4.5mm long and 5.0mm wide, and feebly convex, so that the Tennant specimen must be an external mould. 'Mr Tennant' was presumably James Tennant FGS (1808-1881), the well-known dealer and Professor of Mineralogy and Geology at King's College, London (Cleevely p.285). Fig.2. Original description (A) and figure (B) of...

Earliest known echinoderm — a new Ediacaran fossil from the Pound Subgroup of South Australia

Arkarua adami gen. et sp. nov., a small disc-like animal with a pentameral arrangement of grooves on its oral surface, is preserved as an external mould on the base of sandstone beds within the Ediacaran (Late Precambrian) Ediacara Member of the Pound Subgroup, in the Flinders Ranges. While the limitations of preservation do not allow identification of some important organs, the pentameral symmetry and resemblance to Early Cambrian edrioasteroids enable the recognition of Arkarua as the earliest known echinoderm.

PRESERVATION OF EGGS: III. STUDIES ON THE EFFECT OF OIL TREATMENT AND EGG-CASE LINER BAGS IN THE PRESERVATION OF SHELL EGGS UNDER ADVERSE CONDITIONS

Three replicate lots of eggs, each divided into half-case (15 doz.) sets on the treatments used, were stored at 70° F. and 90% relative humidity for 35 days. Different sets of eggs were conditioned at 32°, 40°, 60°, and 70° F. before being placed in the humidity chamber, but no resulting effect of initial condensate on the eggs and packaging material was demonstrated.Under the conditions of this experiment, oil treatment by the best commercially applicable method, followed by packaging in sealed egg-case liner bags, was found to retard greatly the development of internal defects and severe external mould. Oil treatment alone was definitely beneficial, but the use of egg-case liner bags on untreated eggs was detrimental. While these experiments show that the method of oil treatment combined with bagging was efficacious in these laboratory scale tests, the results obtained from three small test shipments to Great Britain were not in agreement, and indicated that somewhat different storage conditions may be encountered in the export of shell eggs in non-refrigerated holds. The length of time of storage may also be expected to influence directly the degree of spoilage.Differential spoilage of eggs located in the central and top and bottom trays within the case, and at the periphery and in the interior of individual trays, was also noted under certain conditions. This is considered to indicate the importance of humidity gradients within the case.

PRESERVATION OF EGGS: IV. STORAGE OF OILED AND BAGGED EGGS UNDER CONSTANT AND ALTERNATING TEMPERATURES AND HUMIDITIES

Untreated eggs and eggs oiled and sealed in egg-case liner bags were stored for six weeks in standard export cases (a) at 70° F. and 90% relative humidity continuously, (b) at 65° F. and 95% relative humidity alternating with 75° and 70% every two days, the dew point consequently always remaining below 65° F., and (c) at 60° F. alternating with 80° every three days, both at 90% relative humidity, but the dew point varying from 57° to 77° F. respectively. Spoilage was least under the second set of conditions and greatest under the third. The indications were that within rather wide limits, microbiological development was dependent primarily upon storage conditions rather than upon the quantity of inoculum on the surface of the eggs at the beginning of storage. The bags used had little effect on intracase temperatures.Under conditions (a) and (c) oiling and bagging reduced internal mould and rot but did not significantly affect the development of external mould; under conditions (b) internal spoilage was uniformly low in both treated and control eggs. All oiled and bagged eggs were in better physical condition after storage than were the untreated, having smaller air cells, freer yolks, and less distinct yolk shadows. Variations in the incidence of spoilage within cases occurred and are attributed to intracase temperature and humidity differentials.

On Thecospondylus Horneri , a new Dinosaur from the Hastings Sand, indicated by the Sacrum and the Neural Canal of the Sacral Region

Dr. A. C. Horner, of Tonbridge, has obtained from the quarry at Southborough in the Hastings Sand, and intrusted to me, what I believe to be a unique specimen, so far as this country is concerned, exhibiting a mould of the entire neural cavity of the sacral region of a Dinosaur. But the specimen is nevertheless peculiarly tantalizing, since the quarryman states that it is the only specimen of any kind that he has ever found in the quarry, and enough remains of bony tissue upon the cast to render it certain that the external mould of the sacrum, if not the bony tissue itself, might have been preserved. It its imperfect both anteriorly and posteriorly, but measures exactly 60 centimetres in length. The vertebræ which are complete are five in number; each is 11 centim. long; but there is a small fragment in front which appears to show that there was another vertebra anteriorly (fig. 2, 1), while the fragment of the posterior vertebra (fig. 2, 7) admits of no question. We have thus a sacrum which certainly included six or seven vertebræ, and may have comprised more. The bony tissue is preserved only upon the right side of three consecutive vertebræ. It is a thin film closely adherent to the cast, showing a cancellous structure external to the thin interior layer (fig. 1, b ).