FIGURE 5 - uploaded by Dean R. Lomax
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RNHM F5672, hindfin and pelvic elements of Ichthyosaurus conybeari from the Lower Jurassic (Sinemurian) of Lyme RegisCharmouth, Dorset, England. Abbreviations: fe -femur, fi -fibula, il -ilium, is -ischium, ti -tibia, pu -pubis. Scale bar = 5 cm. ____________________________________________________________________________________________________________________ This could suggest the hindfins have been reset into the matrix.
Source publication
Composite fossils can distort our evaluation of the morphology and variation of a species if unrecognised or misidentified. Many Early Jurassic ichthyosaurs collected during the 19th century have been identified as composites, but the problem is not restricted to historic specimens. More recently collected material, including some specimens for sal...
Contexts in source publication
Context 1
... the following set of vertebrae (Figure 1, S4, indicated in red) are yet another block showing the transition from dorsals to caudals, this time possibly from a single individual ( Figure 4B). The next set of vertebrae (Figure 1, S5, colored in yellow) form part of the proximal portion of the tail, once again representing a set of caudal vertebrae. The remaining distal caudals (Figure 1, S6, indicated in dark green, Figure 4C), could belong to the same specimen as the preceding caudals (in yellow), although this cannot be confirmed with certainty. ...
Context 2
... and Pelvis (Real)-The hindfins and pelvis ( Figure 5) are authentic and appear mostly complete. Whether they belong together might be questionable, based solely on the composite nature of the rest of the specimen. ...
Context 3
... the following set of vertebrae (Figure 1, S4, indicated in red) are yet another block showing the transition from dorsals to caudals, this time possibly from a single individual ( Figure 4B). The next set of vertebrae (Figure 1, S5, colored in yellow) form part of the proximal portion of the tail, once again representing a set of caudal vertebrae. The remaining distal caudals (Figure 1, S6, indicated in dark green, Figure 4C), could belong to the same specimen as the preceding caudals (in yellow), although this cannot be confirmed with certainty. ...
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The diets and feeding strategies of pterosaurs remain a poorly known although speculatively debated topic in vertebrate paleontology. Fossilized gut contents, which offer a crucial direct line of evidence to help decipher these elusive questions, are only known from a handful of pterosaur specimens in a few notable fossil Lagerstätten, such as the...
Citations
... In addition, in the UK some specimens may be labelled with locations such as 'Lyme' , 'Whitby' or 'Street' but not only are these sometimes assumptions added long after the fossil has been collected, rather than known facts, these localities cover a broad range of stratigraphical units. Also, collectors, donors or sellers of specimens can be secretive or even deliberately misleading about the actual provenance of a fossil (see Lomax et al. 2022). Whilst data such as the name of the collector or the date of collection may not be recoverable, information regarding the stratigraphical unit or biozone in which the specimen was found can sometimes be recovered by identifying invertebrate macrofossils (e.g. ...
Many museum and university collections contain fossil marine reptile specimens that have no provenance data associated with them, particularly those collected in the 19th and early 20th centuries. This may be because the information was never known to the museum or because the data have since been lost. Moreover, data that are associated with a specimen may have been assumed historically rather than verified and it is known that collectors, donors or sellers of specimens have sometimes been deliberately secretive or even misleading about the actual provenance of the fossils. If invertebrate macrofossils can be identified in
the host matrix of the marine reptile specimen these can sometimes offer clues as to the stratigraphical origin of the specimen, but these instances are rare. Micropalaeontological analyses, however, can be undertaken on relatively small amounts of matrix associated with a specimen to attempt the recovery of lost data or confirm or reject assumed provenance details. Permission has been obtained to take small samples (as little as five grams) of host matrix from the rear of several ichthyosaur specimens during recent conservation projects where the provenance of the specimen was either totally unknown or was in doubt. These samples were analysed for their calcareous microfossil content, including ostracods and foraminifera. It was found that well-cemented limestones contained little or no recoverable material but softer mudstones have sometimes yielded very useful assemblages allowing specific biozones to be attributed to the host specimens, successfully recovering lost data and making the specimens much more useful scientifically. Even when the assemblage of microfauna is found to be poor or absent, some information about the sedimentary conditions of the preservational environment can often be ascertained from the micropalaeontological residues.
