William I Ausich - Profile on Academia.edu (original) (raw)
Papers by William I Ausich
Journal of Paleontology, Jan 14, 2024
Non-technical Summary.-Monstrocrinus is a most unusual crinoid from the Devonian of Germany. It h... more Non-technical Summary.-Monstrocrinus is a most unusual crinoid from the Devonian of Germany. It has long, simple to complex spines attached to most calyx plates. A stem was not associated with the initial specimens on which this genus was named. Thus, it was assumed that Monstrocrinus was a stemless crinoid that sat directly on the sea floor and, when alive, rolled around on its spines. For a variety of reasons, this seems unlikely, but the rolling crinoid lifestyle interpretation has persisted in the literature. More thorough cleaning of historical specimens and, more importantly, a new specimen with an attached column clearly refute the classical lifestyle interpretation and demonstrate that Monstrocrinus was a typical crinoid attached to a long column that was presumably anchored to the sea floor. In addition to revising the lifestyle of this crinoid, the varieties of spine types are redefined with names that more accurately reflect their morphology. Monstrocrinus occurs in Europe and South America, and one previously described species is placed in synonymy so that the genus is now comprised of three species.
Journal of Paleontology, Dec 12, 2023
Blastoid, 'cystoid,' and crinoid fossils (phylum Echinodermata) are described for Silurian strata... more Blastoid, 'cystoid,' and crinoid fossils (phylum Echinodermata) are described for Silurian strata of west-central Ohio. These fossils are from the Cedarville Member of the Laurel Limestone, which is a dolostone rock. All that is preserved in the dolostone are molds and casts of these echinoderms. In the Midcontinent, these rocks were formed in a series of reef and reef-related environments, but the poor preservation of the fossils has hampered their understanding. Crinoids were an important faunal element in these Silurian strata, so this paper is an important step in developing an understanding of these ancient seas. Eleven taxa are described in this fauna, with two new crinoid species.
Treatise online, Jul 9, 2023
A ray. Anterior ray located opposite the posterior (CD) interray; includes radial, succeeding bra... more A ray. Anterior ray located opposite the posterior (CD) interray; includes radial, succeeding brachitaxes and, if present, fixed intrabrachial plates, pinnules, and intrapinnular plates. Other rays are designated B, C, D, and E in clockwise order from A, if viewing adoral side of theca. This schema, the Carpenter Ray System, was proposed by Carpenter (1884 in 1884-1888). AB interray. Interray between A and B rays. Other interrays are designated as BC, CD, DE, and EA in clockwise order from AB if viewing adoral side of theca (syn., anterior right). See A ray. abactinal (syn., aboral, apical, dorsal ). See aboral. abambulacral (adj.). Direction perpendicular to and away from the axis of an ambulacrum (syn., abmedial, abradial). abaxial. Direction away from the oral-aboral axis. abmedial. Away from the medial line of a ray or interray (syn., abambulacral, abradial). aboral. Applied to surface of the body opposite adoral surface; in a typical stalked crinoid, this is the bottom surface where the column attaches to the crown (syn., abactinal, apical, dorsal ). aboral cup. Hard parts of the crinoid from the radial circlet to, but not including, the column. Equivalent to calyx where arms become free on radial plates. (syn., cup; dorsal cup; calyx, if no fixed brachials). aboral element. Terminal, nodose to very long spinose plate forming the proximal plate of roveacrinid calyxes (Hess, etter, & Hagdorn, 2016). aboral ligament fossa. Narrow semicircular depression on aboral side of articular facet of any ray ossicle, serving for attachment of the extensor ligament tissue that connects apposed pairs of plates (syn., dorsal ligament fossa, inner ligament area) See MaCurda & Meyer, 1975, MaCurda, Meyer, & roux, 1978. aboral nerve center (syn., aboral nerve ganglion, chambered organ). See aboral nerve ganglion. aboral nerve ganglion. Five-part (in living crinoids) nerve center of the aboral nervous subsystem positioned in the proximal aboral cup. The ganglion connects to nerves in the column, cirri, and in the crown (syn., aboral nerve center, chambered organ). aboral skeleton. Part of calcareous framework located on aboral side of body; includes columnals, holdfast structures, centrodorsal, cirrals, centrale, lintels, infrabasals, basals, radials, interradial plates, brachials, and pinnulars. aboral subsystem (of the nervous system). Primary subsystem of the crinoid nervous system; proximally the part of the body and surrounds the aboral nerve ganglion. It includes the nerves that penetrate into the column and cirri. Distally above, it forms a pentagonal nerve ring from which branch nerves that continue into the arms. Nervous subsystem that is the primary control for regeneration (syn., entoneural subsystem) (BoHn & Heinzeller, 1999). abortive cirrus. Not applicable to cirri. See abortive radices. abortive radices. Degenerated or abandoned radices evidenced by pimple-like protuberance on columnal latus. Present in Paleozoic clades (adapted from Brett, 1981; see donovan, 2021a). abradial. See abambulacral, abmedial. abthecal. Applied to side of pinnule or pinnular directed away from theca. accessory plate. General designation for any nonnormal plate or interradial plate incorporated into the calyx. Named types of accessory plates include gap plates and intercalaries.
Journal of Paleontology, Mar 1, 2012
Preparing for this presentation, I got hold of a list of Bruce's invited lectures, given during t... more Preparing for this presentation, I got hold of a list of Bruce's invited lectures, given during the past ten years. There are 86 titles on almost as many subjects. I will mention what these presentations were about, so you can get an impression of this Renaissance mind: Carbon isotopes and ocean evolution; Precambrian-Cambrian stratigraphy; Molecular evolution and the fossil record; Ediacaran organisms; Life on Mars; Oxygen and metazoan evolution; Orbital dynamics of the Earth-Moon system; Snowball Earth; Multiplated mollusks; Mass-independent fractionation of sulfur; Biomineralization; The Cambrian Explosion; Geobiology in the Archean; Cross-calibration of geological and astronomical time scales; Origins of biological complexity; Astrobiology of the Earth; Astrobiology of everything else; The Acraman impact of the Ediacaran; Biosignatures in ancient rocks; Microbial metabolism in the Early Archean.
Blastoids from the Cuyahoga Formation of Ohio (Echinodermata; Lower Mississippian)
Kirtlandia., Feb 1, 1996
Exploring Phylogenic Relationships Among Ordovician Crinoids
2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014), Oct 19, 2014
Fused or Hypertrophied Brachials: The Unusual Arms of the Petalocrinidae (Silurian-Devonian, Crinoidea)
GSA Annual Meeting in Indianapolis, Indiana, USA - 2018, 2018
Evolutionary Pathways of the Crinoid Oral Region
2012 GSA Annual Meeting in Charlotte, Nov 4, 2012
Comment and Reply on “Abundant and diverse early Paleozoic infauna indicated by the stratigraphic record”
Geology, 1985
Crypto-Helical Body Plan in Early Echinoderms: New Evidence from the Cambrian Strata of South China
GSA Annual Meeting in Denver, Colorado, USA - 2016, 2016
A Mechanism for Repeated Evolution of Ambulacral Cover Plate Elements in Echinoderms
GSA Annual Meeting in Denver, Colorado, USA - 2016, 2016
Part T, Echinodermata 2 (Revised), vol. 3, Complete Volume
Paleontological Institute, University of Kansas eBooks, 2011
A new Lower Ordovician (middle Canadian) disparid crinoid from Utah
JOURNAL OF PALEONTOLOGY V. 52, NO. 4, P. 916-920, 3 TEXT-FIGS., JULY 1978 ... A NEW LOWER ORDOVIC... more JOURNAL OF PALEONTOLOGY V. 52, NO. 4, P. 916-920, 3 TEXT-FIGS., JULY 1978 ... A NEW LOWER ORDOVICIAN (MIDDLE CANADIAN) DISPARID CRINOID FROM UTAH ... STUART M. KELLY AND WILLIAM I. AUSICH Indiana University, Bloomington 47401
Canadian Journal of Earth Sciences, 2018
Hirnantian (latest Ordovician) localities containing echinoderm fossils are rare; the few that ha... more Hirnantian (latest Ordovician) localities containing echinoderm fossils are rare; the few that have been discovered primarily contain disarticulated crinoid ossicles. Therefore, relatively little is known about echinoderm evolutionary dynamics across the Late Ordovician− early Silurian boundary, especially non-crinoid echinoderms. New diploporitan echinoderms, Holocystites salmoensis and an unidentified holocystitid, from reefal facies of the Upper Ordovician Ellis Bay Formation of Anticosti Island provide a critical data point concerning diploporitan biogeography and evolutionary pathways undertaken during the Ordovician and Silurian. These fossils also provide a crucial link in understanding the ancestry of the Silurian Holocystites Fauna, an unusual diploporitan fauna from the middle Silurian of North America, whose origination dates back at least 15 million years earlier than previously thought with the discovery of taxa described here. New fossil data such as these stress the importance of uncovering new localities from underrepresented times and places in Earth's history, so that these evolutionary transitions can be better understood.
Systematic revisions toAorocrinus, Dorycrinus, Macrocrinus, Paradichocrinus, Strotocrinus, andUperocrinus: Mississippian camerate crinoids (Echinodermata) from the stratotype region
Journal of Paleontology, Nov 1, 1991
Systematic revisions and revised stratigraphic occurrences are made toAorocrinus, Dorycrinus, Mac... more Systematic revisions and revised stratigraphic occurrences are made toAorocrinus, Dorycrinus, Macrocrinus, Paradichocrinus, Strotocrinus, andUperocrinusfrom the Osagean and Meramecian stratotype region in Iowa and Missouri. Systematic revisions include the assignment ofBatocrinus procerusMiller and Gurley as a junior synonym ofMacrocrinus mundulus. Batocrinus heteroclitusMiller and Gurley,B. vicinusMiller and Gurley, andB. stelliformisMiller and Gurley are assigned toUperocrinus heteroclitusn. comb. The concept ofAorocrinus spinosulus(Hall) did not match characteristics of the holotype. Consequently, the appropriate name for this concept isAorocrinus kelloggi(Worthen) n. comb., andA. spinosulusis assigned toDorycrinus mississippiensisas a junior synonym.Batocrinus strenuusis assigned toAorocrinus strenuusn. comb.?; andStrotocrinus glyptusis regarded as the valid name for the only species recognized in this genus.These systematic revisions result in the restriction ofStrotocrinus glyptusto the middle Osagean Burlington Limestone, and extension ofAorocrinus, Dorycrinus, Macrocrinus, andUperocrinusinto the Meramecian upper Warsaw Formation.
Aerosol suspension feeding and current velocities: distributional controls for late Osagean crinoids
Paleobiology, 1987
Distributional patterns of late Osagean (Mississippian) crinoids from the east-central United Sta... more Distributional patterns of late Osagean (Mississippian) crinoids from the east-central United States are examined using multivariate analysis of crinoid species diversity and species abundance data. We confirm previous hypotheses that three well-defined crinoid associations existed during the late Osagean. These associations were dominated, respectively, by 1) monobathrid camerates preserved in carbonate packstones; 2) poteriocrine inadunates in higher-energy siltstones and sandstones; and 3) disparid inadunates, cyathocrine inadunates, and flexibles in mudstones where neither monobathrids nor poteriocrines dominated. In conjunction with petrologic data on the enclosing sediments, the analyses suggest that these associations occurred along a spectrum of increasing current velocity at the seafloor. Camerates, poteriocrine inadunates, and flexibles are interpreted to display preferences for specific environmental conditions, whereas disparid and cyathocrine inadunates are inferred to be environmental generalists.The different environmental distributions of the major crinoid groups are interpreted to be a function of the mode or modes of aerosol filtration feeding used by each group. This inference is possible through functional morphologic and morphometric studies of crinoid arms, because the skeletal elements of the arms, which are commonly preserved, are directly involved in feeding.
First crinoid crown from the Permian Khuff Formation (Wordian) of Oman
Proceedings of the Geologists' Association, Mar 1, 2022
Crinoids and their Paleozoic primacy
An Investigation Into the use of Calcite Fossils as Alpha Thermochronometers
AGU Fall Meeting Abstracts, Dec 1, 2006
ABSTRACT Diffusion studies of He in calcite suggest a potential to use carbonates as an alpha the... more ABSTRACT Diffusion studies of He in calcite suggest a potential to use carbonates as an alpha thermochronometer (Tc ~ 65°C). These results are all from coarse-grained calcite and dolomite but carbonate mud is a common constituent in many limestones. However, coarse calcite can usually be found in even the most micritic limestones in the form of biotic allochems. We have investigated the suitability of using crinoid columnals and shells of the bivalve Inoceramus for alpha thermochronolgy in limestones. After the death of a crinoid, the high-Mg calcite converts to low-Mg calcite with no loss of optical continuity, and the porosity is filled with syntaxial cement thus becoming permineralized. Bivalves undergo typical diagenesis where the high- Mg calcite converts to low-Mg calcite. Two of four crinoid samples yield reasonable alpha ages: A crinoid from the Thrifty Fm. (Pennsylvanian) in Texas gives an age of 120 Ma (0.7-4.0 ppm U) and one from the Edwardsville Fm. of the Borden Group (Lower Mississippian) in Indiana gives an age of 64 Ma (0.9 ppm U). Each of these results are consistent with the tectonic history of the regions. Crinoid pieces from the New Providence Shale Mbr. of the Borden Fm. (Lower Mississippian) in Kentucky have very low [U] (less than 90 ppb) and give Archean ages. Crinoids from the Hughes Creek Shale (Permian) in Kansas have seemingly robust amounts of U (0.7-2.1 ppm) but this sample also seems to be dominated by common He, yielding Proterozoic ages. Inoceramus from the Burditt Fm. of the Austin Gr. (Upper Cretaceous) in Texas gives an age of 0.5 Ma, suggesting that the closure temperature may be much lower than 65°C. Our preliminary conclusion is that crinoid columnals with more than 500 ppb U may be generally suitable for alpha thermochronology but that the closure temperature of He in Inoceramus shells may be too low for geologic application.
Journal of Paleontology, Jan 14, 2024
Non-technical Summary.-Monstrocrinus is a most unusual crinoid from the Devonian of Germany. It h... more Non-technical Summary.-Monstrocrinus is a most unusual crinoid from the Devonian of Germany. It has long, simple to complex spines attached to most calyx plates. A stem was not associated with the initial specimens on which this genus was named. Thus, it was assumed that Monstrocrinus was a stemless crinoid that sat directly on the sea floor and, when alive, rolled around on its spines. For a variety of reasons, this seems unlikely, but the rolling crinoid lifestyle interpretation has persisted in the literature. More thorough cleaning of historical specimens and, more importantly, a new specimen with an attached column clearly refute the classical lifestyle interpretation and demonstrate that Monstrocrinus was a typical crinoid attached to a long column that was presumably anchored to the sea floor. In addition to revising the lifestyle of this crinoid, the varieties of spine types are redefined with names that more accurately reflect their morphology. Monstrocrinus occurs in Europe and South America, and one previously described species is placed in synonymy so that the genus is now comprised of three species.
Journal of Paleontology, Dec 12, 2023
Blastoid, 'cystoid,' and crinoid fossils (phylum Echinodermata) are described for Silurian strata... more Blastoid, 'cystoid,' and crinoid fossils (phylum Echinodermata) are described for Silurian strata of west-central Ohio. These fossils are from the Cedarville Member of the Laurel Limestone, which is a dolostone rock. All that is preserved in the dolostone are molds and casts of these echinoderms. In the Midcontinent, these rocks were formed in a series of reef and reef-related environments, but the poor preservation of the fossils has hampered their understanding. Crinoids were an important faunal element in these Silurian strata, so this paper is an important step in developing an understanding of these ancient seas. Eleven taxa are described in this fauna, with two new crinoid species.
Treatise online, Jul 9, 2023
A ray. Anterior ray located opposite the posterior (CD) interray; includes radial, succeeding bra... more A ray. Anterior ray located opposite the posterior (CD) interray; includes radial, succeeding brachitaxes and, if present, fixed intrabrachial plates, pinnules, and intrapinnular plates. Other rays are designated B, C, D, and E in clockwise order from A, if viewing adoral side of theca. This schema, the Carpenter Ray System, was proposed by Carpenter (1884 in 1884-1888). AB interray. Interray between A and B rays. Other interrays are designated as BC, CD, DE, and EA in clockwise order from AB if viewing adoral side of theca (syn., anterior right). See A ray. abactinal (syn., aboral, apical, dorsal ). See aboral. abambulacral (adj.). Direction perpendicular to and away from the axis of an ambulacrum (syn., abmedial, abradial). abaxial. Direction away from the oral-aboral axis. abmedial. Away from the medial line of a ray or interray (syn., abambulacral, abradial). aboral. Applied to surface of the body opposite adoral surface; in a typical stalked crinoid, this is the bottom surface where the column attaches to the crown (syn., abactinal, apical, dorsal ). aboral cup. Hard parts of the crinoid from the radial circlet to, but not including, the column. Equivalent to calyx where arms become free on radial plates. (syn., cup; dorsal cup; calyx, if no fixed brachials). aboral element. Terminal, nodose to very long spinose plate forming the proximal plate of roveacrinid calyxes (Hess, etter, & Hagdorn, 2016). aboral ligament fossa. Narrow semicircular depression on aboral side of articular facet of any ray ossicle, serving for attachment of the extensor ligament tissue that connects apposed pairs of plates (syn., dorsal ligament fossa, inner ligament area) See MaCurda & Meyer, 1975, MaCurda, Meyer, & roux, 1978. aboral nerve center (syn., aboral nerve ganglion, chambered organ). See aboral nerve ganglion. aboral nerve ganglion. Five-part (in living crinoids) nerve center of the aboral nervous subsystem positioned in the proximal aboral cup. The ganglion connects to nerves in the column, cirri, and in the crown (syn., aboral nerve center, chambered organ). aboral skeleton. Part of calcareous framework located on aboral side of body; includes columnals, holdfast structures, centrodorsal, cirrals, centrale, lintels, infrabasals, basals, radials, interradial plates, brachials, and pinnulars. aboral subsystem (of the nervous system). Primary subsystem of the crinoid nervous system; proximally the part of the body and surrounds the aboral nerve ganglion. It includes the nerves that penetrate into the column and cirri. Distally above, it forms a pentagonal nerve ring from which branch nerves that continue into the arms. Nervous subsystem that is the primary control for regeneration (syn., entoneural subsystem) (BoHn & Heinzeller, 1999). abortive cirrus. Not applicable to cirri. See abortive radices. abortive radices. Degenerated or abandoned radices evidenced by pimple-like protuberance on columnal latus. Present in Paleozoic clades (adapted from Brett, 1981; see donovan, 2021a). abradial. See abambulacral, abmedial. abthecal. Applied to side of pinnule or pinnular directed away from theca. accessory plate. General designation for any nonnormal plate or interradial plate incorporated into the calyx. Named types of accessory plates include gap plates and intercalaries.
Journal of Paleontology, Mar 1, 2012
Preparing for this presentation, I got hold of a list of Bruce's invited lectures, given during t... more Preparing for this presentation, I got hold of a list of Bruce's invited lectures, given during the past ten years. There are 86 titles on almost as many subjects. I will mention what these presentations were about, so you can get an impression of this Renaissance mind: Carbon isotopes and ocean evolution; Precambrian-Cambrian stratigraphy; Molecular evolution and the fossil record; Ediacaran organisms; Life on Mars; Oxygen and metazoan evolution; Orbital dynamics of the Earth-Moon system; Snowball Earth; Multiplated mollusks; Mass-independent fractionation of sulfur; Biomineralization; The Cambrian Explosion; Geobiology in the Archean; Cross-calibration of geological and astronomical time scales; Origins of biological complexity; Astrobiology of the Earth; Astrobiology of everything else; The Acraman impact of the Ediacaran; Biosignatures in ancient rocks; Microbial metabolism in the Early Archean.
Blastoids from the Cuyahoga Formation of Ohio (Echinodermata; Lower Mississippian)
Kirtlandia., Feb 1, 1996
Exploring Phylogenic Relationships Among Ordovician Crinoids
2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014), Oct 19, 2014
Fused or Hypertrophied Brachials: The Unusual Arms of the Petalocrinidae (Silurian-Devonian, Crinoidea)
GSA Annual Meeting in Indianapolis, Indiana, USA - 2018, 2018
Evolutionary Pathways of the Crinoid Oral Region
2012 GSA Annual Meeting in Charlotte, Nov 4, 2012
Comment and Reply on “Abundant and diverse early Paleozoic infauna indicated by the stratigraphic record”
Geology, 1985
Crypto-Helical Body Plan in Early Echinoderms: New Evidence from the Cambrian Strata of South China
GSA Annual Meeting in Denver, Colorado, USA - 2016, 2016
A Mechanism for Repeated Evolution of Ambulacral Cover Plate Elements in Echinoderms
GSA Annual Meeting in Denver, Colorado, USA - 2016, 2016
Part T, Echinodermata 2 (Revised), vol. 3, Complete Volume
Paleontological Institute, University of Kansas eBooks, 2011
A new Lower Ordovician (middle Canadian) disparid crinoid from Utah
JOURNAL OF PALEONTOLOGY V. 52, NO. 4, P. 916-920, 3 TEXT-FIGS., JULY 1978 ... A NEW LOWER ORDOVIC... more JOURNAL OF PALEONTOLOGY V. 52, NO. 4, P. 916-920, 3 TEXT-FIGS., JULY 1978 ... A NEW LOWER ORDOVICIAN (MIDDLE CANADIAN) DISPARID CRINOID FROM UTAH ... STUART M. KELLY AND WILLIAM I. AUSICH Indiana University, Bloomington 47401
Canadian Journal of Earth Sciences, 2018
Hirnantian (latest Ordovician) localities containing echinoderm fossils are rare; the few that ha... more Hirnantian (latest Ordovician) localities containing echinoderm fossils are rare; the few that have been discovered primarily contain disarticulated crinoid ossicles. Therefore, relatively little is known about echinoderm evolutionary dynamics across the Late Ordovician− early Silurian boundary, especially non-crinoid echinoderms. New diploporitan echinoderms, Holocystites salmoensis and an unidentified holocystitid, from reefal facies of the Upper Ordovician Ellis Bay Formation of Anticosti Island provide a critical data point concerning diploporitan biogeography and evolutionary pathways undertaken during the Ordovician and Silurian. These fossils also provide a crucial link in understanding the ancestry of the Silurian Holocystites Fauna, an unusual diploporitan fauna from the middle Silurian of North America, whose origination dates back at least 15 million years earlier than previously thought with the discovery of taxa described here. New fossil data such as these stress the importance of uncovering new localities from underrepresented times and places in Earth's history, so that these evolutionary transitions can be better understood.
Systematic revisions toAorocrinus, Dorycrinus, Macrocrinus, Paradichocrinus, Strotocrinus, andUperocrinus: Mississippian camerate crinoids (Echinodermata) from the stratotype region
Journal of Paleontology, Nov 1, 1991
Systematic revisions and revised stratigraphic occurrences are made toAorocrinus, Dorycrinus, Mac... more Systematic revisions and revised stratigraphic occurrences are made toAorocrinus, Dorycrinus, Macrocrinus, Paradichocrinus, Strotocrinus, andUperocrinusfrom the Osagean and Meramecian stratotype region in Iowa and Missouri. Systematic revisions include the assignment ofBatocrinus procerusMiller and Gurley as a junior synonym ofMacrocrinus mundulus. Batocrinus heteroclitusMiller and Gurley,B. vicinusMiller and Gurley, andB. stelliformisMiller and Gurley are assigned toUperocrinus heteroclitusn. comb. The concept ofAorocrinus spinosulus(Hall) did not match characteristics of the holotype. Consequently, the appropriate name for this concept isAorocrinus kelloggi(Worthen) n. comb., andA. spinosulusis assigned toDorycrinus mississippiensisas a junior synonym.Batocrinus strenuusis assigned toAorocrinus strenuusn. comb.?; andStrotocrinus glyptusis regarded as the valid name for the only species recognized in this genus.These systematic revisions result in the restriction ofStrotocrinus glyptusto the middle Osagean Burlington Limestone, and extension ofAorocrinus, Dorycrinus, Macrocrinus, andUperocrinusinto the Meramecian upper Warsaw Formation.
Aerosol suspension feeding and current velocities: distributional controls for late Osagean crinoids
Paleobiology, 1987
Distributional patterns of late Osagean (Mississippian) crinoids from the east-central United Sta... more Distributional patterns of late Osagean (Mississippian) crinoids from the east-central United States are examined using multivariate analysis of crinoid species diversity and species abundance data. We confirm previous hypotheses that three well-defined crinoid associations existed during the late Osagean. These associations were dominated, respectively, by 1) monobathrid camerates preserved in carbonate packstones; 2) poteriocrine inadunates in higher-energy siltstones and sandstones; and 3) disparid inadunates, cyathocrine inadunates, and flexibles in mudstones where neither monobathrids nor poteriocrines dominated. In conjunction with petrologic data on the enclosing sediments, the analyses suggest that these associations occurred along a spectrum of increasing current velocity at the seafloor. Camerates, poteriocrine inadunates, and flexibles are interpreted to display preferences for specific environmental conditions, whereas disparid and cyathocrine inadunates are inferred to be environmental generalists.The different environmental distributions of the major crinoid groups are interpreted to be a function of the mode or modes of aerosol filtration feeding used by each group. This inference is possible through functional morphologic and morphometric studies of crinoid arms, because the skeletal elements of the arms, which are commonly preserved, are directly involved in feeding.
First crinoid crown from the Permian Khuff Formation (Wordian) of Oman
Proceedings of the Geologists' Association, Mar 1, 2022
Crinoids and their Paleozoic primacy
An Investigation Into the use of Calcite Fossils as Alpha Thermochronometers
AGU Fall Meeting Abstracts, Dec 1, 2006
ABSTRACT Diffusion studies of He in calcite suggest a potential to use carbonates as an alpha the... more ABSTRACT Diffusion studies of He in calcite suggest a potential to use carbonates as an alpha thermochronometer (Tc ~ 65°C). These results are all from coarse-grained calcite and dolomite but carbonate mud is a common constituent in many limestones. However, coarse calcite can usually be found in even the most micritic limestones in the form of biotic allochems. We have investigated the suitability of using crinoid columnals and shells of the bivalve Inoceramus for alpha thermochronolgy in limestones. After the death of a crinoid, the high-Mg calcite converts to low-Mg calcite with no loss of optical continuity, and the porosity is filled with syntaxial cement thus becoming permineralized. Bivalves undergo typical diagenesis where the high- Mg calcite converts to low-Mg calcite. Two of four crinoid samples yield reasonable alpha ages: A crinoid from the Thrifty Fm. (Pennsylvanian) in Texas gives an age of 120 Ma (0.7-4.0 ppm U) and one from the Edwardsville Fm. of the Borden Group (Lower Mississippian) in Indiana gives an age of 64 Ma (0.9 ppm U). Each of these results are consistent with the tectonic history of the regions. Crinoid pieces from the New Providence Shale Mbr. of the Borden Fm. (Lower Mississippian) in Kentucky have very low [U] (less than 90 ppb) and give Archean ages. Crinoids from the Hughes Creek Shale (Permian) in Kansas have seemingly robust amounts of U (0.7-2.1 ppm) but this sample also seems to be dominated by common He, yielding Proterozoic ages. Inoceramus from the Burditt Fm. of the Austin Gr. (Upper Cretaceous) in Texas gives an age of 0.5 Ma, suggesting that the closure temperature may be much lower than 65°C. Our preliminary conclusion is that crinoid columnals with more than 500 ppb U may be generally suitable for alpha thermochronology but that the closure temperature of He in Inoceramus shells may be too low for geologic application.