The Red Crag Formation (upper Pliocene-lower Pleistocene) yielded many vertebrate coprolites in t... more The Red Crag Formation (upper Pliocene-lower Pleistocene) yielded many vertebrate coprolites in the late Nineteenth Century as a result of coprolite mining. Indeed, coprolite mining had a significant impact on the development of vertebrate paleontology in Victorian England. The Red Crag Formation consists principally of shell-rich sandstones that formed in a high energy, shallow marine environment. The Suffolk Bone Bed is a discontinuous conglomerate at or near the base of the formation that yields phosphatic nodules, diverse reworked clasts, chondrichthyan teeth, abraded specimens of marine and nonmarine vertebrates and phosphatic vertebrate coprolites. Helicocoprus clarki igen. and isp. nov. is a distinctive amphipolar coprolite from the Red Crag Formation. The spiral morphology and large size of this Cenozoic coprolite indicates that it was produced by a chondrichthyan and possibly a member of the Rajidae.
A partial shell of the well-known Upper Cretaceous turtle Adocus was collected in the Crevasse Ca... more A partial shell of the well-known Upper Cretaceous turtle Adocus was collected in the Crevasse Canyon Formation, east of the Caballo Mountains in Sierra County, New Mexico. It was found stratigraphically low in the Crevasse Canyon Formation, so its age is close to the Coniacian-Santonian boundary (approximately 86 Ma). This is the southernmost known occurrence of an Adocus in North America and may be the oldest North American record of the genus. A fragmentary specimen was previously reported from Santonian strata in Utah and tentatively assigned to the genus based on surface sculpture. The specimen from the Crevasse Canyon Formation is the anterior half of the plastron as well as most of the free edge of the anterior half of the carapace. This includes a partial nuchal bone missing a portion of its left half. In addition to this, are many isolated shell fragments of indeterminate placement. The Crevasse Canyon specimen has several features that justify assigning it to the genus Ado...
Vertebrate coprolites from the Cretaceous Chalk of England were among the first to be described a... more Vertebrate coprolites from the Cretaceous Chalk of England were among the first to be described and identified. Coprolites occur commonly in the Cenomanian Grey Chalk Group and the Turonian-Maastrichtian White Chalk Group. A small number of coprolites have been described from the chalk of Denmark, Netherlands, Belgium, Germany and Poland. Coprolites are abundant in the Niobrara Formation of Kansas but poorly studied. A single specimen has been described from the Selma Chalk of Alabama. Coprolites are facies fossils, and their distribution reflects that of the producing organism. The majority of chalk coprolites are spiral, and their most distinctive characteristic seems to be that in lateral view there are many thin coils in which margins are thin and crenulated, which gives the general appearance of a fir cone. The majority of specimens are heteropolar, although a small number are amphipolar, including Iuloeidocoprus mantelli. The heteropolar coprolites are macrospiral. Vertebrate coprolites are clearly common, at least in the English and Kansas chalk, and there is a need for further collection and study. There is a disparity between the high taxonomic diversity of fish faunas in chalk (and other marine facies) and the low diversity of chondrichthyan-dominated coprolite ichnofaunas which we term the "shark surplus paradox.
The Upper Cretaceous (Campanian) Menefee Formation is a dominantly nonmarine formation, which con... more The Upper Cretaceous (Campanian) Menefee Formation is a dominantly nonmarine formation, which contains a wide variety of incomplete turtle fossils, including remains of adocids, trionychids, baenids, bothremydids, and the solemydid turtle Naomichelys. Two specimens of Denazinemys and one refered to aff. Denazinemys have been recovered from the Menefee Formation. Additionally, mixed in are five pieces that appear to be from a turtle pelvic girdle. These may represent the first girdle material associated with a specimen of Denazinemys. Additional indeterminate baenid specimens include specimen NMMNH [NM Museum of Natural History] P-70340, which includes two large pieces of the lateral edge of the anterior plastral lobe. The one specimen of the solemydid turtle Naomichelys is a small, ~4 cm diameter piece of turtle shell bone with the characteristic pattern of raised circles seen in this genus. This represents the only record of Naomichelys from New Mexico. Trionychids in the Menefee F...
The Eocene turtles of the San Juan Basin, New Mexico, were last reviewed over a century ago as co... more The Eocene turtles of the San Juan Basin, New Mexico, were last reviewed over a century ago as comprising 15 species in seven genera and five families. However, many of these species are based on non-diagnostic, fragmentary material and are thus nomina dubia. We conclude that there are six valid species of fossil turtles known from the Eocene San Jose Formation. These include Baena arenosa and Hadrianus majusculus, previously recognized from these strata. Further, we combine Echmatemys cibolensis into E. lativertebralis. All San Jose trionychid specimens lack diagnostic types and are referred to Trionychidae indeterminate. Finally, more recent collections include fragmentary specimens attributable to Baptemys garmani and Planetochelys dithyros. Overall, the San Jose turtle fauna is less diverse than that of the Willwood Formation, lacking the testudinoid turtles Cardichelyon and Psilosemys as well as the families Kinosternidae and Chelydridae. Conversely, the San Jose turtle fauna is more diverse than the turtle fauna of the Golden Valley Formation of North Dakota, which lacks Hadrianus. The San Jose turtle assemblage is consistent with an assignment to the Lysitean sub-land-mammal “age,” in agreement with the age previously assessed based on the mammal fossils.
We describe several juvenile Echmatemys shell fragments and thereby establish some aspects of thi... more We describe several juvenile Echmatemys shell fragments and thereby establish some aspects of this species ontogeny. We thus identify two major ontogenetic changes from juvenile to adult specimens. Along the medial line of the carapace in juveniles there is a well-developed median keel that flattens as the turtle ages, and the plastron appears to elongate significantly relative to its width during development. Based on this new understanding of ontogenetic variation in Echmatemys, we recognize E. testudinea and E. megaulax as junior subjective synonyms of E. lativertebralis.
Fragments of turtle shell are known from several Cretaceous formations in New Mexico, including t... more Fragments of turtle shell are known from several Cretaceous formations in New Mexico, including the Mancos Shale, Tres Hermanos Formation, Crevasse Canyon Formation, Point Lookout Sandstone, Menefee Formation, Pierre Shale, Ringbone Formation, Fruitland Formation, Kirtland Formation, Ojo Alamo Formation and McRae Formation. Of these, the Tres Hermanos Formation, Mancos Formation, Point Lookout Sandstone, Dalton Member of the Crevasse Canyon Formation and Ringbone Formation have only yielded remains of trionychids. This is largely because most of these units are shoreline sandstones of the Western Interior seaway that contain extensive shark-tooth assemblages with a mixture of a few fragmentary freshwater vertebrate fossils, including those of trionychids. The more terrestrial units of the Crevasse Canyon, Menefee, Fruitland, Kirtland and Ojo Alamo formations yield a more diverse array of fossil turtles, generally consisting of trionychids, baenids and adocids. Among the baenid turtles is the oldest reported record of Denazinemys and an indeterminate bothremydid turtle from the Menefee Formation. In addition to these, the Menefee Formation also yields the first known specimen of Naomichelys from the Cretaceous of New Mexico. The Pierre Shale yields one fossil turtle species, the marine turtle Archelon sp. Further exploration of the Cretaceous strata of New Mexico, especially the Crevasse Canyon and Menefee formations, should yield a much more extensive record of fossil turtles.
The Eocene (late Wasatchian-early Bridgerian) Huerfano Formation in the northern Raton basin of s... more The Eocene (late Wasatchian-early Bridgerian) Huerfano Formation in the northern Raton basin of southeastern Colorado yields a fossil turtle assemblage representing several taxa. Most of these come from fossil mammal localities, and the majority are specimens of Hadrianus and indeterminate trionychids. In addition, Huerfano turtles include the southernmost report of Echmatemys stevensoni and a possible specimen of Plastomenus lachrymalis. Additionally, a single ~50% complete shell is assigned to a new taxon, Baltemys velogastros, sp. nov. The Huerfano Formation turtle assemblage resembles other similar-aged turtle assemblages in western North America except that it lacks baenid turtles and Baptemys. However, given the uneven and incomplete sampling of turtle fossils from the Huerfano Formation, current conclusions drawn from it are tentative and preliminary.
The Piceance Creek Basin is a late Laramide depositional basin in northwestern Colorado with a Pa... more The Piceance Creek Basin is a late Laramide depositional basin in northwestern Colorado with a Paleocene-Eocene basin fill ranging in age from Tiffanian to Wasatchian (and younger). The Tiffanian-Wasatchian strata, assigned to the Fort Union and Wasatch formations (= DeBeque Formation), have yielded a variety of little-studied fossil turtles. These include indeterminate adocids, the dermatemydid Baptemys, chelydrids, trionychids and Echmatemys similar to E. lativertebralis. We concur with the reassignment of “Paleotrionyx” quinni to the genus Axestemys. Additionally, there are bones of the platysternid Cardichelyon present, but these are indeterminate to the species level because they have an unusual hypoplastron compared to the type of that genus. Material with the typical ornamentation of Compsemys is found in the Fort Union Formation, but more specific identification is not possible. Overall, the biostratigraphic distribution of turtle taxa in the Fort Union and Wasatch formations follows the pattern seen in the Willwood Formation of Wyoming. This may indicate the presence of a widespread Tiffanian-Wasatchian turtle fauna preserved in several temporally overlapping late Laramide basins.
The Red Crag Formation (upper Pliocene-lower Pleistocene) yielded many vertebrate coprolites in t... more The Red Crag Formation (upper Pliocene-lower Pleistocene) yielded many vertebrate coprolites in the late Nineteenth Century as a result of coprolite mining. Indeed, coprolite mining had a significant impact on the development of vertebrate paleontology in Victorian England. The Red Crag Formation consists principally of shell-rich sandstones that formed in a high energy, shallow marine environment. The Suffolk Bone Bed is a discontinuous conglomerate at or near the base of the formation that yields phosphatic nodules, diverse reworked clasts, chondrichthyan teeth, abraded specimens of marine and nonmarine vertebrates and phosphatic vertebrate coprolites. Helicocoprus clarki igen. and isp. nov. is a distinctive amphipolar coprolite from the Red Crag Formation. The spiral morphology and large size of this Cenozoic coprolite indicates that it was produced by a chondrichthyan and possibly a member of the Rajidae.
A partial shell of the well-known Upper Cretaceous turtle Adocus was collected in the Crevasse Ca... more A partial shell of the well-known Upper Cretaceous turtle Adocus was collected in the Crevasse Canyon Formation, east of the Caballo Mountains in Sierra County, New Mexico. It was found stratigraphically low in the Crevasse Canyon Formation, so its age is close to the Coniacian-Santonian boundary (approximately 86 Ma). This is the southernmost known occurrence of an Adocus in North America and may be the oldest North American record of the genus. A fragmentary specimen was previously reported from Santonian strata in Utah and tentatively assigned to the genus based on surface sculpture. The specimen from the Crevasse Canyon Formation is the anterior half of the plastron as well as most of the free edge of the anterior half of the carapace. This includes a partial nuchal bone missing a portion of its left half. In addition to this, are many isolated shell fragments of indeterminate placement. The Crevasse Canyon specimen has several features that justify assigning it to the genus Ado...
Vertebrate coprolites from the Cretaceous Chalk of England were among the first to be described a... more Vertebrate coprolites from the Cretaceous Chalk of England were among the first to be described and identified. Coprolites occur commonly in the Cenomanian Grey Chalk Group and the Turonian-Maastrichtian White Chalk Group. A small number of coprolites have been described from the chalk of Denmark, Netherlands, Belgium, Germany and Poland. Coprolites are abundant in the Niobrara Formation of Kansas but poorly studied. A single specimen has been described from the Selma Chalk of Alabama. Coprolites are facies fossils, and their distribution reflects that of the producing organism. The majority of chalk coprolites are spiral, and their most distinctive characteristic seems to be that in lateral view there are many thin coils in which margins are thin and crenulated, which gives the general appearance of a fir cone. The majority of specimens are heteropolar, although a small number are amphipolar, including Iuloeidocoprus mantelli. The heteropolar coprolites are macrospiral. Vertebrate coprolites are clearly common, at least in the English and Kansas chalk, and there is a need for further collection and study. There is a disparity between the high taxonomic diversity of fish faunas in chalk (and other marine facies) and the low diversity of chondrichthyan-dominated coprolite ichnofaunas which we term the "shark surplus paradox.
The Upper Cretaceous (Campanian) Menefee Formation is a dominantly nonmarine formation, which con... more The Upper Cretaceous (Campanian) Menefee Formation is a dominantly nonmarine formation, which contains a wide variety of incomplete turtle fossils, including remains of adocids, trionychids, baenids, bothremydids, and the solemydid turtle Naomichelys. Two specimens of Denazinemys and one refered to aff. Denazinemys have been recovered from the Menefee Formation. Additionally, mixed in are five pieces that appear to be from a turtle pelvic girdle. These may represent the first girdle material associated with a specimen of Denazinemys. Additional indeterminate baenid specimens include specimen NMMNH [NM Museum of Natural History] P-70340, which includes two large pieces of the lateral edge of the anterior plastral lobe. The one specimen of the solemydid turtle Naomichelys is a small, ~4 cm diameter piece of turtle shell bone with the characteristic pattern of raised circles seen in this genus. This represents the only record of Naomichelys from New Mexico. Trionychids in the Menefee F...
The Eocene turtles of the San Juan Basin, New Mexico, were last reviewed over a century ago as co... more The Eocene turtles of the San Juan Basin, New Mexico, were last reviewed over a century ago as comprising 15 species in seven genera and five families. However, many of these species are based on non-diagnostic, fragmentary material and are thus nomina dubia. We conclude that there are six valid species of fossil turtles known from the Eocene San Jose Formation. These include Baena arenosa and Hadrianus majusculus, previously recognized from these strata. Further, we combine Echmatemys cibolensis into E. lativertebralis. All San Jose trionychid specimens lack diagnostic types and are referred to Trionychidae indeterminate. Finally, more recent collections include fragmentary specimens attributable to Baptemys garmani and Planetochelys dithyros. Overall, the San Jose turtle fauna is less diverse than that of the Willwood Formation, lacking the testudinoid turtles Cardichelyon and Psilosemys as well as the families Kinosternidae and Chelydridae. Conversely, the San Jose turtle fauna is more diverse than the turtle fauna of the Golden Valley Formation of North Dakota, which lacks Hadrianus. The San Jose turtle assemblage is consistent with an assignment to the Lysitean sub-land-mammal “age,” in agreement with the age previously assessed based on the mammal fossils.
We describe several juvenile Echmatemys shell fragments and thereby establish some aspects of thi... more We describe several juvenile Echmatemys shell fragments and thereby establish some aspects of this species ontogeny. We thus identify two major ontogenetic changes from juvenile to adult specimens. Along the medial line of the carapace in juveniles there is a well-developed median keel that flattens as the turtle ages, and the plastron appears to elongate significantly relative to its width during development. Based on this new understanding of ontogenetic variation in Echmatemys, we recognize E. testudinea and E. megaulax as junior subjective synonyms of E. lativertebralis.
Fragments of turtle shell are known from several Cretaceous formations in New Mexico, including t... more Fragments of turtle shell are known from several Cretaceous formations in New Mexico, including the Mancos Shale, Tres Hermanos Formation, Crevasse Canyon Formation, Point Lookout Sandstone, Menefee Formation, Pierre Shale, Ringbone Formation, Fruitland Formation, Kirtland Formation, Ojo Alamo Formation and McRae Formation. Of these, the Tres Hermanos Formation, Mancos Formation, Point Lookout Sandstone, Dalton Member of the Crevasse Canyon Formation and Ringbone Formation have only yielded remains of trionychids. This is largely because most of these units are shoreline sandstones of the Western Interior seaway that contain extensive shark-tooth assemblages with a mixture of a few fragmentary freshwater vertebrate fossils, including those of trionychids. The more terrestrial units of the Crevasse Canyon, Menefee, Fruitland, Kirtland and Ojo Alamo formations yield a more diverse array of fossil turtles, generally consisting of trionychids, baenids and adocids. Among the baenid turtles is the oldest reported record of Denazinemys and an indeterminate bothremydid turtle from the Menefee Formation. In addition to these, the Menefee Formation also yields the first known specimen of Naomichelys from the Cretaceous of New Mexico. The Pierre Shale yields one fossil turtle species, the marine turtle Archelon sp. Further exploration of the Cretaceous strata of New Mexico, especially the Crevasse Canyon and Menefee formations, should yield a much more extensive record of fossil turtles.
The Eocene (late Wasatchian-early Bridgerian) Huerfano Formation in the northern Raton basin of s... more The Eocene (late Wasatchian-early Bridgerian) Huerfano Formation in the northern Raton basin of southeastern Colorado yields a fossil turtle assemblage representing several taxa. Most of these come from fossil mammal localities, and the majority are specimens of Hadrianus and indeterminate trionychids. In addition, Huerfano turtles include the southernmost report of Echmatemys stevensoni and a possible specimen of Plastomenus lachrymalis. Additionally, a single ~50% complete shell is assigned to a new taxon, Baltemys velogastros, sp. nov. The Huerfano Formation turtle assemblage resembles other similar-aged turtle assemblages in western North America except that it lacks baenid turtles and Baptemys. However, given the uneven and incomplete sampling of turtle fossils from the Huerfano Formation, current conclusions drawn from it are tentative and preliminary.
The Piceance Creek Basin is a late Laramide depositional basin in northwestern Colorado with a Pa... more The Piceance Creek Basin is a late Laramide depositional basin in northwestern Colorado with a Paleocene-Eocene basin fill ranging in age from Tiffanian to Wasatchian (and younger). The Tiffanian-Wasatchian strata, assigned to the Fort Union and Wasatch formations (= DeBeque Formation), have yielded a variety of little-studied fossil turtles. These include indeterminate adocids, the dermatemydid Baptemys, chelydrids, trionychids and Echmatemys similar to E. lativertebralis. We concur with the reassignment of “Paleotrionyx” quinni to the genus Axestemys. Additionally, there are bones of the platysternid Cardichelyon present, but these are indeterminate to the species level because they have an unusual hypoplastron compared to the type of that genus. Material with the typical ornamentation of Compsemys is found in the Fort Union Formation, but more specific identification is not possible. Overall, the biostratigraphic distribution of turtle taxa in the Fort Union and Wasatch formations follows the pattern seen in the Willwood Formation of Wyoming. This may indicate the presence of a widespread Tiffanian-Wasatchian turtle fauna preserved in several temporally overlapping late Laramide basins.
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