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- 저자 : (Dale A . Winkler) (검색결과 4 건)
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PALEOENVIRONMENT AT JONES RANCH, AN EARLY CRETACEOUS SAUROPOD QUARRY IN TEXAS, U.S.A.
Dale A. Winkler,Peter J. Rose 한국고생물학회 2006 고생물학회지 Vol.22 No.1
Jones Ranch는 미국 텍사스 Twin Mountains층 (Trinity 층군)의 전기 백악기 (Aptian-Albian 경계) 용각류 공룡들이 함께 묻혀있는 독특한 화석지다. 최소한 4개체의 뼈들이 하성 퇴적물 속에 커다란 나무 둥치들과 함께 묻혀있다. 퇴적구조, 화석화과정, 함께 산출되는 동식물 화석군을 보면 계절적으로 건기 때 용각류 시체와 나무들이 함께 썩은 후 운반되어 재배치되어 현재 위치에 온 것으로 해석된다. 함께 산출되는 척추동물화석들은 육성환경과 민물에 사는 hybodont chondrichthyan Lonchidion enitae와 폐어를 포함한다. 본 화석지에 풍부한 식물화적은 멸종된 침엽수인 Frenelopsis ramosissima 이다. 그 당시 Jones Ranch에는 용각류들이 생물의 다양성이 그리 높지 않은 20 미터 높이에 이르는 침엽수림에 살고 있었다. Trinity 층군에서 산출되는 풍부한 발자국화석과 이들 용각류 화석들은 용각류들이 얕은 해안을 따라 발달한 높은 다양성을 가지는 숲과 계절적으로 가문 다양성이 낮은 내륙 숲속 모두에 군집을 이루며 살았다는 것을 암시한다. Jones Ranch is a unique Early Cretaceous (Aptian-Albian boundary) sauropod dinosaur accumulation in the Twin Mountains Formation (Trinity Group), Texas, U.S.A. Bones of at least four individuals are found together with large logs in a fluvial channel deposit. Sedimentary structures, taphonomic considerations and associated fauna and flora demonstrate that sauropod carcasses and trees decomposed in a seasonally dry stream bed before being transported to, or rearranged at, their final point of burial. Associated vertebrate fauna includes terrestrial and fresh water elements including the rare hybodont chondrichthyan Lonchidion anitae and lungfish. Abundant plant material from the site is referred to the extinct conifer Frenelopsis ramosissima. At Jones Ranch, sauropods dwelt within a low diversity coniferous forest with trees that reached above 20 meters in height. The death assemblage and abundant track sites in the Trinity Group suggest gregarious behavior in a sauropod that occupied both low diversity inland forests drained by ephemeral streams and higher diversity plant communities along the coast of a shallow sea.
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Diagenesis of dinosaur eggshell from the Gobi Desert, Mongolia
Graf, John,Tabor, Neil J.,Ferguson, Kurt,Winkler, Dale A.,Lee, Yuong-Nam,May, Steven,Jacobs, Louis L. Elsevier 2018 Palaeogeography, palaeoclimatology, palaeoecology Vol.494 No.-
<P><B>Abstract</B></P> <P>In order to test for paleoenvironmental and paleoecological parameters important in dinosaur evolution, thirty-four fragments of dinosaur eggshell, paleosol carbonates from six localities, and calcite crystals from inside a dinosaur femur were collected from the Campanian to Maastrichtian Baruungoyot and Nemegt formations, Gobi Desert, Mongolia. The samples were examined for diagenesis using light microscopy, SEM, and cathodoluminescence, and each was analyzed for δ<SUP>13</SUP>C and δ<SUP>18</SUP>O values. Eggshell isotope values plot along two trends of enrichment, with paleosol carbonate nodule values plotting along locality specific trends. Convergence of the trends suggests similar initial conditions among localities. Permian-age detrital zircons in the fossiliferous sediment suggest that enriched eggshell and paleosol carbonate nodule δ<SUP>13</SUP>C values may have been caused by phreatic zone diagenetic alteration by waters with an aqueous bicarbonate component derived from interaction and dissolution of Permian calcareous marine host rocks. Our hypothetical model for eggshell diagenesis assumes a stable carbon- and oxygen-isotope domain space delimited by three end members: (1) apparently unaltered eggshell with primary microstructure, (2) non-luminescent eggshell with no preserved microstructure, and (3) luminescent eggshell with no preserved microstructure. The two end members showing no preservation of microstructure indicate different phases of diagenetic alteration in the presence of vadose and phreatic waters. None of the samples analyzed can be shown to be sufficiently unaltered for analysis using standard techniques. Biologically, eggshell is porous to facilitate the movement of gases while an embryo is developing within the egg. Geologically, that same property allows the flow of diagenetic ground waters, which modifies the primary isotopic signature of eggshell.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Stable isotopes in dinosaur eggshell are used to infer paleobiology and paleoenvironment. </LI> <LI> However, porosity that facilitates movement of gases, makes fossil eggshells prone to diagenesis. </LI> <LI> δ<SUP>13</SUP>C and δ<SUP>18</SUP>O in Mongolian Cretaceous eggshell from the Gobi Desert indicate rampant diagenesis. </LI> <LI> Eggshell was subjected to shallow-burial, vadose and phreatic zone diagenesis. </LI> </UL> </P>
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Su-Hwan Kim,Yuong-Nam Lee,Jin-Young Park,Sungjin Lee,Dale A. Winkler,Louis L. Jacobs,Rinchen Barsbold 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10
Compared to abundant dinosaur faunas, fish materials are scarce in the Nemegt Formation (Upper Cretaceous) of Mongolia. Only one report was about isolated centra assigned to the Hiodontidae (Osteoglossomopha). Here we report new additional fish materials collected from the Nemegt Formation during the Korea-Mongolia International Dinosaur Expedition (KID, 2006~2010). They include skull parts (quadrate, premaxilla, and dentary), isolated and articulated centra, and a caudal fin. New specimens appear to be the same taxon as the reported old samples based on morphological similarities in the abdominal centra. However, the suggested features for identifying the hiodontids are erroneous. All specimens represent a new genus and species of osteoglossomorph fish, Harenaichthys lui gen. et sp. nov. Furthermore, phylogenetic analysis reveals that Harenaichthys is a basal member of the osteoglossomorphs instead of being included in the hiodontids. By identifying a fish centrum associated with the theropod dinosaur Raptorex kriegsteini as Harenaichthys, we concluded that R. kriegsteini comes from the Nemegt Formation. Unusual monospecific occurrences of Harenaichthys allow us to understand their paleoecology and paleobiogeography better. In addition, the pathologic features seen on some centra of Harenaicthys indicate that they suffered from various diseases in life.
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