ABSTRACT Partial eggs from the Eocene Willwood Formation of Wyoming contain unidentifiable embryonic remains; the eggs are referable to a theropod on the basis of their structural layering of calcite and to an avian theropod because of their Eocene age. We assign the specimens to the oofamily Medioolithidae as Microolithus wilsoni, oogen. et oosp. nov., on the basis of the following unique combination of characters: 600-μm-thick eggshell composed of three structural layers; abrupt and undulating contact between the mammillary and continuous layers; smooth and glossy outer egg surface; faint or obscure prisms of the continuous layer; non-branching pores; and mammillary-to-total shell thickness ratio of 1:4. The eggshell microstructure resembles that of some extant neognath bird eggs. We refer a single egg from Chadron Formation of eastern Nebraska to incertae sedis as Metoolithus nebraskensis, oogen. et oosp. nov. A combination of characters distinguishes the egg from other fossil and modern avian eggs, namely, thicker eggshell, prominent ornamentation, flared upper portion of the prisms, variable mammillary thickness, and irregular squamatic texture in the continuous layer. These characteristics more closely resemble Mesozoic non-avian theropod eggs and likely reflect mosaic evolution in the non-avian to avian-theropod transition. Finally, an external layer occurs in a wide range of Paleogene and Cretaceous eggs of variable size and taxonomic affinities, indicating that this feature may not represent an apomorphic character for the avian crown group with respect to non-avian theropod eggshell. Therefore, an external layer cannot be used to identify neognath birds in the Mesozoic.
Testudo antiqua is one of the few fossil turtle names to have survived the past 200 years of taxonomic reshuffling with its original genus and specific epithet intact. The nine currently known specimens were collected from the middle Miocene Hohenhöwen locality in southern Germany. Because the available Hohenhöwen material was never fully described, we here completely document all known specimens. It is unclear which of these specimens formed the original T. antiqua type series, so we herein selected the best preserved representative as the neotype. A phylogenetic analysis places T. antiqua in a basal polytomy within the clade Testudo , indicating that T. antiqua may represent the ancestral morphology of Testudo . As with a number of other published studies, ours was unable to resolve relationships between the three extant Testudo lineages (the hermanni -group, the graeca / kleinmanni / marginata group, and the horsfieldii -group). Finally, with a view toward locating more turtles and in order to better understand the geological and ecological context of these tortoises, we visited Hohenhöwen several times to search for the original collection sites, but we were unable to locate the original fossil quarries described in the literature.
ABSTRACTIn this paper, we describe a new species of a giant tortoise, Cheirogaster bacharidisi, sp. nov., from the Pliocene (Gonia Formation) of western Chalkidiki Peninsula, near Thessaloniki, Greece. The specimens constitute the most complete giant tortoise found to date in Greece, and provide materials for direct comparison with other described European forms. We assign it to the genus Cheirogaster, as opposed to Centrochelys, based upon the convex dorsal surface of the epiplastron. Direct comparison with material from Europe shows that it differs from other giant tortoises attributed to Cheirogaster mainly in cranial and plastral morphology. Exceptional postcranial preservation allows the description of many skeletal elements, previously unknown or poorly described for Cheirogaster, as well as for a reappraisal of the previously published specimens from Greece.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at http://www.tandfonline.com/UJVP. ACKNOWLEDGMENTSThe authors express their sincere thanks to the researchers involved in the excavation and collection of specimens, especially N. Bacharidis, G. Lazarides, H. Luett, K. Chantzarides, A. Tzanoudakis, and A. Xanthis. We would like to thank G. Syrides and K. Vasileiadou for their help with stratigraphy; A. Pérez-García for valuable comments and information about Spanish material; and T. Kotsakis (Laboratorio di Paleontologia dei Vertebrati, Roma Tre). We thank F. de Lapparent de Broin for discussions on the material in the MNHN. Valuable comments from reviewers F. de Lapparent de Broin and M. Rabi (University of Tübingen) greatly improved the manuscript. S. Modesto is thanked for editorial work. For access to collections, we would like to thank G. Theodorou and S. Roussiakis (AMPG), M. Harzhauser and U. Göhlich (NHMW), R. Allain and B. Battail (MNHN), M. Moser (BSPG), H. Furrer (PIMUZ), and S. Scherrer (NWS).Handling editor: Sean Modesto
In 2005, a 550-acre tract of agricultural land containing two small streams near La Grande, Oregon was registered in the U.S. Federal Wetlands Reserve Program. This designation was part of a plan to reclaim and restore the wetland to its natural state. Initial efforts at the End Creek Restoration Project restored both End Creek and South Fork Willow Creek to a natural course through rechanneling, and several plantings had restored some of the native flora. Since its establishment, the End Creek streams and floodplain have become a reserve for summer steelhead (Oncorhynchus mykiss), a threatened anadromous salmonid, and many migratory birds. The threatened Columbia Spotted Frog has also established itself in some of the ponds. As part of an effort to establish a baseline for water quality, we monitored total springtime coliform and fecal coliform bacteria in three of the End Creek ponds for three years. The results of this study indicate that, throughout any given spring, the numbers of both coliform and fecal coliform bacteria can fluctuate markedly among ponds on any given day, and that in any particular pond the numbers fluctuate from week to week. In addition, our analysis suggests that in early spring, the numbers of these organisms also fluctuate from year to year. The causes of these fluctuations are not well understood, but are expected to reflect both springtime flooding and the migrations of source animals such as waterfowl and cervids. Information gathered from this study will help inform future management activities on the wetland.
Taphonomic studies of extant turtles are useful for interpreting the taphonomy of fossil turtles. In order to provide modern comparators for fossil turtle sites, we have characterized two modern turtle (Chrysemys picta) deathsites; one in northwestern Nebraska and one in southwestern South Dakota. During these studies we characterized carapace position (up or down), presence or absence of non-shell elements, relative spatial position of the turtles and presence of shell disturbances (lesions). In the Trunk Butte site (Nebraska), six turtles were in carapace up position, five were in carapace down and one was not determinable. In addition, seven of those turtles contained some non-shell elements and five had indeterminable non-shell element status. At the Buffalo Gap site (South Dakota), four were carapace down, two were carapace up and three were not determinable for that character. Six of these had non-shell elements associated with them and three had no non-shell elements. The occurrence of turtles in the carapace down position suggests either the presence of medium to large scavengers able to overturn a turtle or that the turtle died while in the water and overturned while sinking. The spatial distributions of turtles in the two modern sites were also plotted and compared to that of two Whitney (Brule Formation, White River Group) and one Chadron (White River Group) site to address the hypothesis that the fossil assemblages were associated with small ponds. The results suggest that the fossil turtle sites were not the result of death events associated with small ponds, nullifying that hypothesis.
Variation in the Shell Elements of Chrysemys picta bellii (Gray 1831) Assignment of fossil turtle shell elements to a specific taxon is often difficult because the range of variation within the population is usually not well characterized. In addition, it is sometimes not clear whether the fossil forms actually differ from their extant counterparts because often the range of shell element variation in modern species has not been determined. The emydid turtles are no exception, with confusion often arising in the identification of isolated fossil elements and sometimes intact shells representing Emys, Pseudemys, Malaclemys, and Graptemys, as well as the deirochelyids Chrysemys, Clemmys, Deirochelys, and Trachemys. In order to begin providing a database with modern counterparts of the deirochelyid turtles, I have photographed and illustrated seven extant Chrysemys picta bellii shells, six of which were collected at a single pond in Nebraska and one from Ladd Marsh in Union County, Oregon . Photographs and detailed illustrations indicate a broad range in the shapes of many characters. Side by side comparisons of some key elements show that there is significant variation in several important characters (nuchal shape/sulci, entoplastron shape/sulci, and pygal shape/sulci). I also conducted a limited morphometric analysis of several sulcus/suture distance ratios, showing substantial variation between individuals in some cases. Covariance and correlation analysis of this variation suggests that allometry is not involved in most cases. In summary, this work provides a visual and morphometric dataset for aid in identifying and assigning shell elements of fossil emydid turtles.
Testudo antiqua is one of the few fossil turtle names to have survived the past 200 years of taxonomic reshuffling with its original genus and specific epithet intact. The nine currently known specimens were collected from the middle Miocene Hohenhöwen locality in southern Germany. Because the available Hohenhöwen material was never fully described, we here completely document all known specimens. It is unclear which of these specimens formed the original T. antiqua type series, so we herein selected the best preserved representative as the neotype. A phylogenetic analysis places T. antiqua in a basal polytomy within the clade Testudo , indicating that T. antiqua may represent the ancestral morphology of Testudo . As with a number of other published studies, ours was unable to resolve relationships between the three extant Testudo lineages (the hermanni -group, the graeca / kleinmanni / marginata group, and the horsfieldii -group). Finally, with a view toward locating more turtles and in order to better understand the geological and ecological context of these tortoises, we visited Hohenhöwen several times to search for the original collection sites, but we were unable to locate the original fossil quarries described in the literature.
Turtles are the most common vertebrates in the upper Eocene and lower Oligocene rocks of Nebraska. In this work we characterize a striking decline in overall turtle abundance in the early Oligocene at two Nebraska localities: Toadstool Park and Scotts Bluff National Monument. In both locations, this decline occurs at a prominent change in rock composition, the contact between the Orella and Whitney members of the Brule Formation. The two study sites are 140 km apart, suggesting that this decline in turtle fossils was a regional event. Although the reasons for the abundance changes are not entirely clear, we present preservation biases or regional cooling and drying as competing hypotheses.
