Chris Noto | University of Wisconsin-Parkside (original) (raw)

Papers by Chris Noto

PeerJ, 2022

While the terrestrial fossil record of the mid-Cretaceous interval (Aptian to Cenomanian) in Nort... more While the terrestrial fossil record of the mid-Cretaceous interval (Aptian to Cenomanian) in North America has been poorly studied, the recent focus on fossil localities from the western United States has offered a more detailed picture of vertebrate diversity, ecosystem dynamics and faunal turnover that took place on the western landmass of Laramidia. This is in stark contrast to the terrestrial record from the eastern landmass of Appalachia, where vertebrate fossils are rare and consist mostly of isolated and fragmentary remains. However, a detailed understanding of these fossil communities during this interval is necessary for comparison of the faunal patterns that developed during the opening of the Western Interior Seaway (WIS). The Woodbine Group of Texas is a Cenomanian age (95–100 mya) deposit consisting of shallow marine, deltaic, and terrestrial communities, which were only recently separated from their western counterparts. These deposits have yielded a wealth of vertebra...

Journal of Vertebrate Paleontology, 2017

ABSTRACT A new taxon of neosuchian crocodyliform, Deltasuchus motherali, gen. et sp. nov., is des... more ABSTRACT A new taxon of neosuchian crocodyliform, Deltasuchus motherali, gen. et sp. nov., is described on the basis of a partial skull recovered from the Arlington Archosaur Site within the Upper Cretaceous (Cenomanian) Woodbine Formation of north-central Texas. This productive locality represents a delta plain ecosystem preserving a diverse coastal fauna, including lungfish, turtles, dinosaurs (ornithopods and theropods), and crocodyliforms. Prior to this discovery, the only identified crocodyliforms from the Woodbine Formation had been the longirostrine taxa Terminonaris and Woodbinesuchus. This new taxon is differentiated from other known crocodyliforms by the presence of dual pseudocanines on both the dentary and maxilla; anterior and posterior rami of jugal comparable in depth; anterolaterally facing margin on the dorsal portion of the postorbital; contact between the descending process of the postorbital and the ectopterygoid; and a large, deep fossa on the ventral surface of the quadrate. Phylogenetic analysis recovers D. motherali as the sister taxon to Paluxysuchus newmani from the Lower Cretaceous Twin Mountains Formation of Texas. This clade lies within Neosuchia basal to Goniopholididae + Eusuchia. The associated cranial elements of this new crocodyliform represent a large, broad-snouted individual, an ecomorphotype often associated with the semiaquatic ambush predator niche in this clade, and one not previously reported from the formation.

PALAIOS, 2012

Direct evidence of behavior in extinct tetrapods is rare. However, these traces can inform a vari... more Direct evidence of behavior in extinct tetrapods is rare. However, these traces can inform a variety of research questions touching on paleoecology, taphonomy, and functional morphology. Here we present fossil specimens from the Upper Cretaceous (Cenomanian) Woodbine Formation that exhibit tooth marks consistent with predation by a new taxon of large crocodyliform currently under study. Collected from the recently discovered Arlington Archosaur Site, the marked bones were largely found in a single peat horizon and in close association with the new crocodyliform. The feeding traces themselves consist of pits, scores, and punctures that occur on multiple turtle shell fragments and two dinosaur limb bones. The pattern of marks and the breakage on turtle carapaces and plastra suggest that they were crushed, whereas the marks on dinosaur bones indicate possible dismemberment. These interpretations and the association with a crocodyliform trace maker are based on observations of feeding behaviors and accompanying, diagnostic bite mark patterns made by extant crocodylians. The morphology of the new crocodyliform taxon and the distribution of bite marks indicates it was likely a generalist: an opportunistic predator that fed on a variety of prey, including turtles and dinosaurs. Given this evidence and the paleoenvironmental setting, the ecology of the large crocodyliform from the Woodbine Formation was likely most similar to that of fossil and living crocodylians inhabiting delta-plain environments. Not only were these crocodyliforms likely significant predators in the Woodbine paleoecosystem, they also played an important taphonomic role in the assembly of vertebrate remains from the surrounding community.

Topics in Geobiology, 2010

PloS one, Jan 3, 2010

There have been numerous studies on dinosaur biogeographic distribution patterns. However, these ... more There have been numerous studies on dinosaur biogeographic distribution patterns. However, these distribution data have not yet been applied to ecological questions. Ecological studies of dinosaurs have tended to focus on reconstructing individual taxa, usually through comparisons to modern analogs. Fewer studies have sought to determine if the ecological structure of fossil assemblages is preserved and, if so, how dinosaur communities varied. Climate is a major component driving differences between communities. If the ecological structure of a fossil locality is preserved, we expect that dinosaur assemblages from similar environments will share a similar ecological structure. This study applies Ecological Structure Analysis (ESA) to a dataset of 100+ dinosaur taxa arranged into twelve composite fossil assemblages from around the world. Each assemblage was assigned a climate zone (biome) based on its location. Dinosaur taxa were placed into ecomorphological categories. The proportio...

PeerJ, 2014

Shed dinosaur teeth are commonly collected microvertebrate remains that have been used for interp... more Shed dinosaur teeth are commonly collected microvertebrate remains that have been used for interpretations of dinosaur feeding behaviors, paleoecology, and population studies. However, such interpretations may be biased by taphonomic processes such as fluvial sorting influenced by tooth shape: shed teeth, removed from the skull during life, and teeth possessing roots, removed from the skull after death. As such, teeth may behave differently in fluvial systems due to their differences in shape. In order to determine the influence of fluvial processes on the preservation and distribution of shed and root-bearing dinosaur teeth, the hydrodynamic behaviors of high-density urethane resin casts of shed and root-bearing Allosaurus and Camarasaurus teeth were experimentally tested for relative transport distances at increasing flow velocities in an artificial fluviatile environment. Results show that tooth cast specimens exhibited comparable patterns of transport at lower velocities, though the shed Camarasaurus teeth transported considerably farther in medium to higher flow velocities. Two-Way ANOVA tests indicate significant differences in the mean transport distances of tooth casts oriented perpendicular to flow (p < 0.05) with varying tooth morphologies and flow velocities. The differences exhibited in the transportability of shed and root-bearing teeth has important implications for taphonomic reconstructions, as well as future studies on dinosaur population dynamics, paleoecology, and feeding behaviors.

A new taxon of neosuchian crocodyliform, Deltasuchus motherali, gen. et sp. nov., is described on... more A new taxon of neosuchian crocodyliform, Deltasuchus motherali, gen. et sp. nov., is described on the basis of a partial skull recovered from the Arlington Archosaur Site within the Upper Cretaceous (Cenomanian) Woodbine Formation of north-central Texas. This productive locality represents a delta plain ecosystem preserving a diverse coastal fauna, including lungfish, turtles, dinosaurs (ornithopods and theropods), and crocodyliforms. Prior to this discovery, the only identified crocodyliforms from the Woodbine Formation had been the longirostrine taxa Terminonaris and Woodbinesuchus. This new taxon is differentiated from other known crocodyliforms by the presence of dual pseudocanines on both the dentary and maxilla; anterior and posterior rami of jugal comparable in depth; anterolaterally facing margin on the dorsal portion of the postorbital; contact between the descending process of the postorbital and the ectopterygoid; and a large, deep fossa on the ventral surface of the quadrate. Phylogenetic analysis recovers D. motherali as the sister taxon to Paluxysuchus newmani from the Lower Cretaceous Twin Mountains Formation of Texas. This clade lies within Neosuchia basal to Goniopholididae + Eusuchia. The associated cranial elements of this new crocodyliform represent a large, broad-snouted individual, an ecomorphotype often associated with the semiaquatic ambush predator niche in this clade, and one not previously reported from the formation.

PLoS1, Sep 3, 2010

Background: There have been numerous studies on dinosaur biogeographic distribution patterns. How... more Background: There have been numerous studies on dinosaur biogeographic distribution patterns. However, these distribution data have not yet been applied to ecological questions. Ecological studies of dinosaurs have tended to focus on reconstructing individual taxa, usually through comparisons to modern analogs. Fewer studies have sought to determine if the ecological structure of fossil assemblages is preserved and, if so, how dinosaur communities varied. Climate is a major component driving differences between communities. If the ecological structure of a fossil locality is preserved, we expect that dinosaur assemblages from similar environments will share a similar ecological structure.

The Alvarezsauridae are an enigmatic family of theropod dinosaurs, characterized by derived forms... more The Alvarezsauridae are an enigmatic family of theropod dinosaurs, characterized by derived forms that possess extremely short forelimbs with a single functional digit bearing a large robust ungual. Alvarezsauridae are first recorded from the Late Jurassic Shishugou Formation of China (Haplocheirus), but are otherwise known only from the Late Cretaceous, particularly South America (Alnashetri; Alvarezsaurus; Patagonykus) and Asia (Xixianykus; Linhenykus; Parvicursor; Shuvuuia; Mononykus) including a number of relatively complete skeletons. In contrast, the North American Late Cretaceous has yielded only limited material, comprising an ulna, manual ungual, tibiae, metatarsals and phalanges (Albertonykus) from the Lower Maastrichtian part of the Horseshoe Canyon Formation, Alberta; and a pubis, partial ischium, and a metatarsal from the Upper Maastrichtian Hell Creek Formation (Montana) and Lance Formation (Wyoming).

The transect from Jones Ranch Quarry, west of the town of Glen Rose, to the Arlington Archosaur S... more The transect from Jones Ranch Quarry, west of the town of Glen Rose, to the Arlington Archosaur Site, in the heart of the Dallas-Fort Worth Metroplex, spans 20 million years of the middle Cretaceous. These sediments lie at the base of a larger section in north-central Texas with near continuous sedimentation to the end of the Maastrichtian. At an even grander scale this is a small part of Cretaceous strata that crop out extensively across the state, forming a broad band roughly parallel with the present day coast of the Gulf of Mexico. This field trip visits Cretaceous strata in the Fort Worth Basin, that is one of the main archosaur fossil-bearing regions of the state.

Direct evidence of behavior in extinct tetrapods is rare. However, these traces can inform a vari... more Direct evidence of behavior in extinct tetrapods is rare. However, these traces can inform a variety of research questions touching on paleoecology, taphonomy, and functional morphology. Here we present fossil specimens from the Upper Cretaceous (Cenomanian) Woodbine Formation that exhibit tooth marks consistent with predation by a new taxon of large crocodyliform currently under study. Collected from the recently discovered Arlington Archosaur Site, the marked bones were largely found in a single peat horizon and in close association with the new crocodyliform. The feeding traces themselves consist of pits, scores, and punctures that occur on multiple turtle shell fragments and two dinosaur limb bones. The pattern of marks and the breakage on turtle carapaces and plastra suggest that they were crushed, whereas the marks on dinosaur bones indicate possible dismemberment. These interpretations and the association with a crocodyliform trace maker are based on observations of feeding behaviors and accompanying, diagnostic bite mark patterns made by extant crocodylians. The morphology of the new crocodyliform taxon and the distribution of bite marks indicates it was likely a generalist: an opportunistic predator that fed on a variety of prey, including turtles and dinosaurs. Given this evidence and the paleoenvironmental setting, the ecology of the large crocodyliform from the Woodbine Formation was likely most similar to that of fossil and living crocodylians inhabiting delta-plain environments. Not only were these crocodyliforms likely significant predators in the Woodbine paleoecosystem, they also played an important taphonomic role in the assembly of vertebrate remains from the surrounding community.

Shed dinosaur teeth are commonly collected microvertebrate remains that have been used for interp... more Shed dinosaur teeth are commonly collected microvertebrate remains that have been used for interpretations of dinosaur feeding behaviors, paleoecology, and population studies. However, such interpretations may be biased by taphonomic processes such as fluvial sorting influenced by tooth shape: shed teeth, removed from the skull during life, and teeth possessing roots, removed from the skull after death. As such, teeth may behave differently in fluvial systems due to their differences in shape. In order to determine the influence of fluvial processes on the preservation and distribution of shed and root-bearing dinosaur teeth, the hydrodynamic behaviors of high-density urethane resin casts of shed and root-bearing Allosaurus and Camarasaurus teeth were experimentally tested for relative transport distances at increasing flow velocities in an artificial fluviatile environment. Results show that tooth cast specimens exhibited comparable patterns of transport at lower velocities, though the shed Camarasaurus teeth transported considerably farther in medium to higher flow velocities. Two-Way ANOVA tests indicate significant differences in the mean transport distances of tooth casts oriented perpendicular to flow (p < 0.05) with varying tooth morphologies and flow velocities. The differences exhibited in the transportability of shed and root-bearing teeth has important implications for taphonomic reconstructions, as well as future studies on dinosaur population dynamics, paleoecology, and feeding behaviors. Subjects Paleontology Peterson JE, Bigalke CL. 2013. Hydrodynamic behaviors of pachycephalosaurid domes in controlled fluvial settings: a case study in experimental dinosaur taphonomy. Palaios 28(5):285-292 DOI 10.2110/palo.2013.p13-003r. Peterson JE, Scherer RP, Huffman KM. 2011. Methods of microvertebrate sampling and their influences on taphonomic interpretations. Palaios 26:81-88 DOI 10.2110/palo.2010.p10-080r. Roach BT, Brinkman DL. 2007. A reevaluation of cooperative pack hunting and gregariousness in Deinonychus antirrhopus and other nonavian theropod dinosaurs.

Taphonomy, Second Edition, Nov 2010

There is no doubt among paleontologists that the fossil record of terrestrial vertebrates is frag... more There is no doubt among paleontologists that the fossil record of terrestrial vertebrates is fragmented and unevenly distributed
over space and time. The underlying causes of this patchiness derive from a combination of factors occurring before and after
the deposition of vertebrate remains. Large-scale vertebrate fossil distribution patterns present challenges in addressing
the effects of small-scale taphonomic processes on distribution patterns, and what, if any, effect they may have on biodiversity
reconstructions. This chapter presents a hierarchical model connecting small-scale taphonomic processes and large-scale fossil
preservation patterns. Factors acting at higher levels in the hierarchy constrain the range of taphonomic processes acting
at lower levels, whereas lower level processes are responsible for determining vertebrate preservation and the resulting fossil
record for an area. Secular changes in climate, tectonics, sea-level, etc. alter the distribution of both environments and
biodiversity over time. These changes in turn may alter the congruence between standing biodiversity and the fraction of that
diversity faithfully represented in the fossil record, skewing our understanding of extinct vertebrate ecosystems and their
evolution over time.

Background: There have been numerous studies on dinosaur biogeographic distribution patterns. How... more Background: There have been numerous studies on dinosaur biogeographic distribution patterns. However, these distribution data have not yet been applied to ecological questions. Ecological studies of dinosaurs have tended to focus on reconstructing individual taxa, usually through comparisons to modern analogs. Fewer studies have sought to determine if the ecological structure of fossil assemblages is preserved and, if so, how dinosaur communities varied. Climate is a major component driving differences between communities. If the ecological structure of a fossil locality is preserved, we expect that dinosaur assemblages from similar environments will share a similar ecological structure.

Talks by Chris Noto

Our understanding of the complex faunal transitions taking place through the Early to Late Cretac... more Our understanding of the complex faunal transitions taking place through the Early to Late Cretaceous interval in North America is critical in reconstructing the complex biogeographic and evolutionary forces that drove the reorganization of Late Cretaceous terrestrial ecosystems. However, this record is based almost exclusively on fossil deposits from Laramidia, on the western side of the Interior Seaway. Little is known about faunal dynamics on the eastern landmass of Appalachia, especially during the early Late Cretaceous. The Woodbine Formation of north-central Texas was deposited during the middle Cenomanian (95-100 mya) and represents a coastal delta ecosystem. Knowledge of the Woodbine ecosystem has been greatly expanded with the recent discovery of the Arlington Archosaur Site (AAS), which preserves an extraordinarily diverse assemblage of dinosaurs, crocodyliforms, turtles, mammals, amphibians, chondrichthyans, osteichthyans, and plants. Sedimentary data suggest a strongly seasonal climate with a monsoonal wet season followed by a pronounced dry season that experienced periodic wildfires. When combined with previously described Woodbine taxa a picture emerges of a distinct transitional fauna characterized by Early Cretaceous groups including derived allosauroids, nodosaurid ankylosaurs, neosuchian crocodyliforms, and basal cryptodiran turtles mixed with early representatives of Late Cretaceous communities such as basal hadrosauroids, dromaeosaurids, troodontids, eusuchian crocodyliforms, and baenid and trionychoid turtles. Overall the Woodbine is similar in taxonomic composition to equivalent Laramidian deposits, yet share few genera in common supporting a widespread distribution of these groups prior to formation of the Interior Seaway. The Woodbine Formation shows the faunal transition in North America was an ongoing, gradual process that continued throughout the Cenomanian. This suggests that the characteristic Late Cretaceous communities assembled slowly, possibly representing a previously unrecognized community structure unique to this interval, and do not represent a rapid turnover event.

PeerJ, 2022

While the terrestrial fossil record of the mid-Cretaceous interval (Aptian to Cenomanian) in Nort... more While the terrestrial fossil record of the mid-Cretaceous interval (Aptian to Cenomanian) in North America has been poorly studied, the recent focus on fossil localities from the western United States has offered a more detailed picture of vertebrate diversity, ecosystem dynamics and faunal turnover that took place on the western landmass of Laramidia. This is in stark contrast to the terrestrial record from the eastern landmass of Appalachia, where vertebrate fossils are rare and consist mostly of isolated and fragmentary remains. However, a detailed understanding of these fossil communities during this interval is necessary for comparison of the faunal patterns that developed during the opening of the Western Interior Seaway (WIS). The Woodbine Group of Texas is a Cenomanian age (95–100 mya) deposit consisting of shallow marine, deltaic, and terrestrial communities, which were only recently separated from their western counterparts. These deposits have yielded a wealth of vertebra...

Journal of Vertebrate Paleontology, 2017

ABSTRACT A new taxon of neosuchian crocodyliform, Deltasuchus motherali, gen. et sp. nov., is des... more ABSTRACT A new taxon of neosuchian crocodyliform, Deltasuchus motherali, gen. et sp. nov., is described on the basis of a partial skull recovered from the Arlington Archosaur Site within the Upper Cretaceous (Cenomanian) Woodbine Formation of north-central Texas. This productive locality represents a delta plain ecosystem preserving a diverse coastal fauna, including lungfish, turtles, dinosaurs (ornithopods and theropods), and crocodyliforms. Prior to this discovery, the only identified crocodyliforms from the Woodbine Formation had been the longirostrine taxa Terminonaris and Woodbinesuchus. This new taxon is differentiated from other known crocodyliforms by the presence of dual pseudocanines on both the dentary and maxilla; anterior and posterior rami of jugal comparable in depth; anterolaterally facing margin on the dorsal portion of the postorbital; contact between the descending process of the postorbital and the ectopterygoid; and a large, deep fossa on the ventral surface of the quadrate. Phylogenetic analysis recovers D. motherali as the sister taxon to Paluxysuchus newmani from the Lower Cretaceous Twin Mountains Formation of Texas. This clade lies within Neosuchia basal to Goniopholididae + Eusuchia. The associated cranial elements of this new crocodyliform represent a large, broad-snouted individual, an ecomorphotype often associated with the semiaquatic ambush predator niche in this clade, and one not previously reported from the formation.

PALAIOS, 2012

Direct evidence of behavior in extinct tetrapods is rare. However, these traces can inform a vari... more Direct evidence of behavior in extinct tetrapods is rare. However, these traces can inform a variety of research questions touching on paleoecology, taphonomy, and functional morphology. Here we present fossil specimens from the Upper Cretaceous (Cenomanian) Woodbine Formation that exhibit tooth marks consistent with predation by a new taxon of large crocodyliform currently under study. Collected from the recently discovered Arlington Archosaur Site, the marked bones were largely found in a single peat horizon and in close association with the new crocodyliform. The feeding traces themselves consist of pits, scores, and punctures that occur on multiple turtle shell fragments and two dinosaur limb bones. The pattern of marks and the breakage on turtle carapaces and plastra suggest that they were crushed, whereas the marks on dinosaur bones indicate possible dismemberment. These interpretations and the association with a crocodyliform trace maker are based on observations of feeding behaviors and accompanying, diagnostic bite mark patterns made by extant crocodylians. The morphology of the new crocodyliform taxon and the distribution of bite marks indicates it was likely a generalist: an opportunistic predator that fed on a variety of prey, including turtles and dinosaurs. Given this evidence and the paleoenvironmental setting, the ecology of the large crocodyliform from the Woodbine Formation was likely most similar to that of fossil and living crocodylians inhabiting delta-plain environments. Not only were these crocodyliforms likely significant predators in the Woodbine paleoecosystem, they also played an important taphonomic role in the assembly of vertebrate remains from the surrounding community.

Topics in Geobiology, 2010

PloS one, Jan 3, 2010

There have been numerous studies on dinosaur biogeographic distribution patterns. However, these ... more There have been numerous studies on dinosaur biogeographic distribution patterns. However, these distribution data have not yet been applied to ecological questions. Ecological studies of dinosaurs have tended to focus on reconstructing individual taxa, usually through comparisons to modern analogs. Fewer studies have sought to determine if the ecological structure of fossil assemblages is preserved and, if so, how dinosaur communities varied. Climate is a major component driving differences between communities. If the ecological structure of a fossil locality is preserved, we expect that dinosaur assemblages from similar environments will share a similar ecological structure. This study applies Ecological Structure Analysis (ESA) to a dataset of 100+ dinosaur taxa arranged into twelve composite fossil assemblages from around the world. Each assemblage was assigned a climate zone (biome) based on its location. Dinosaur taxa were placed into ecomorphological categories. The proportio...

PeerJ, 2014

Shed dinosaur teeth are commonly collected microvertebrate remains that have been used for interp... more Shed dinosaur teeth are commonly collected microvertebrate remains that have been used for interpretations of dinosaur feeding behaviors, paleoecology, and population studies. However, such interpretations may be biased by taphonomic processes such as fluvial sorting influenced by tooth shape: shed teeth, removed from the skull during life, and teeth possessing roots, removed from the skull after death. As such, teeth may behave differently in fluvial systems due to their differences in shape. In order to determine the influence of fluvial processes on the preservation and distribution of shed and root-bearing dinosaur teeth, the hydrodynamic behaviors of high-density urethane resin casts of shed and root-bearing Allosaurus and Camarasaurus teeth were experimentally tested for relative transport distances at increasing flow velocities in an artificial fluviatile environment. Results show that tooth cast specimens exhibited comparable patterns of transport at lower velocities, though the shed Camarasaurus teeth transported considerably farther in medium to higher flow velocities. Two-Way ANOVA tests indicate significant differences in the mean transport distances of tooth casts oriented perpendicular to flow (p < 0.05) with varying tooth morphologies and flow velocities. The differences exhibited in the transportability of shed and root-bearing teeth has important implications for taphonomic reconstructions, as well as future studies on dinosaur population dynamics, paleoecology, and feeding behaviors.

A new taxon of neosuchian crocodyliform, Deltasuchus motherali, gen. et sp. nov., is described on... more A new taxon of neosuchian crocodyliform, Deltasuchus motherali, gen. et sp. nov., is described on the basis of a partial skull recovered from the Arlington Archosaur Site within the Upper Cretaceous (Cenomanian) Woodbine Formation of north-central Texas. This productive locality represents a delta plain ecosystem preserving a diverse coastal fauna, including lungfish, turtles, dinosaurs (ornithopods and theropods), and crocodyliforms. Prior to this discovery, the only identified crocodyliforms from the Woodbine Formation had been the longirostrine taxa Terminonaris and Woodbinesuchus. This new taxon is differentiated from other known crocodyliforms by the presence of dual pseudocanines on both the dentary and maxilla; anterior and posterior rami of jugal comparable in depth; anterolaterally facing margin on the dorsal portion of the postorbital; contact between the descending process of the postorbital and the ectopterygoid; and a large, deep fossa on the ventral surface of the quadrate. Phylogenetic analysis recovers D. motherali as the sister taxon to Paluxysuchus newmani from the Lower Cretaceous Twin Mountains Formation of Texas. This clade lies within Neosuchia basal to Goniopholididae + Eusuchia. The associated cranial elements of this new crocodyliform represent a large, broad-snouted individual, an ecomorphotype often associated with the semiaquatic ambush predator niche in this clade, and one not previously reported from the formation.

PLoS1, Sep 3, 2010

Background: There have been numerous studies on dinosaur biogeographic distribution patterns. How... more Background: There have been numerous studies on dinosaur biogeographic distribution patterns. However, these distribution data have not yet been applied to ecological questions. Ecological studies of dinosaurs have tended to focus on reconstructing individual taxa, usually through comparisons to modern analogs. Fewer studies have sought to determine if the ecological structure of fossil assemblages is preserved and, if so, how dinosaur communities varied. Climate is a major component driving differences between communities. If the ecological structure of a fossil locality is preserved, we expect that dinosaur assemblages from similar environments will share a similar ecological structure.

The Alvarezsauridae are an enigmatic family of theropod dinosaurs, characterized by derived forms... more The Alvarezsauridae are an enigmatic family of theropod dinosaurs, characterized by derived forms that possess extremely short forelimbs with a single functional digit bearing a large robust ungual. Alvarezsauridae are first recorded from the Late Jurassic Shishugou Formation of China (Haplocheirus), but are otherwise known only from the Late Cretaceous, particularly South America (Alnashetri; Alvarezsaurus; Patagonykus) and Asia (Xixianykus; Linhenykus; Parvicursor; Shuvuuia; Mononykus) including a number of relatively complete skeletons. In contrast, the North American Late Cretaceous has yielded only limited material, comprising an ulna, manual ungual, tibiae, metatarsals and phalanges (Albertonykus) from the Lower Maastrichtian part of the Horseshoe Canyon Formation, Alberta; and a pubis, partial ischium, and a metatarsal from the Upper Maastrichtian Hell Creek Formation (Montana) and Lance Formation (Wyoming).

The transect from Jones Ranch Quarry, west of the town of Glen Rose, to the Arlington Archosaur S... more The transect from Jones Ranch Quarry, west of the town of Glen Rose, to the Arlington Archosaur Site, in the heart of the Dallas-Fort Worth Metroplex, spans 20 million years of the middle Cretaceous. These sediments lie at the base of a larger section in north-central Texas with near continuous sedimentation to the end of the Maastrichtian. At an even grander scale this is a small part of Cretaceous strata that crop out extensively across the state, forming a broad band roughly parallel with the present day coast of the Gulf of Mexico. This field trip visits Cretaceous strata in the Fort Worth Basin, that is one of the main archosaur fossil-bearing regions of the state.

Direct evidence of behavior in extinct tetrapods is rare. However, these traces can inform a vari... more Direct evidence of behavior in extinct tetrapods is rare. However, these traces can inform a variety of research questions touching on paleoecology, taphonomy, and functional morphology. Here we present fossil specimens from the Upper Cretaceous (Cenomanian) Woodbine Formation that exhibit tooth marks consistent with predation by a new taxon of large crocodyliform currently under study. Collected from the recently discovered Arlington Archosaur Site, the marked bones were largely found in a single peat horizon and in close association with the new crocodyliform. The feeding traces themselves consist of pits, scores, and punctures that occur on multiple turtle shell fragments and two dinosaur limb bones. The pattern of marks and the breakage on turtle carapaces and plastra suggest that they were crushed, whereas the marks on dinosaur bones indicate possible dismemberment. These interpretations and the association with a crocodyliform trace maker are based on observations of feeding behaviors and accompanying, diagnostic bite mark patterns made by extant crocodylians. The morphology of the new crocodyliform taxon and the distribution of bite marks indicates it was likely a generalist: an opportunistic predator that fed on a variety of prey, including turtles and dinosaurs. Given this evidence and the paleoenvironmental setting, the ecology of the large crocodyliform from the Woodbine Formation was likely most similar to that of fossil and living crocodylians inhabiting delta-plain environments. Not only were these crocodyliforms likely significant predators in the Woodbine paleoecosystem, they also played an important taphonomic role in the assembly of vertebrate remains from the surrounding community.

Shed dinosaur teeth are commonly collected microvertebrate remains that have been used for interp... more Shed dinosaur teeth are commonly collected microvertebrate remains that have been used for interpretations of dinosaur feeding behaviors, paleoecology, and population studies. However, such interpretations may be biased by taphonomic processes such as fluvial sorting influenced by tooth shape: shed teeth, removed from the skull during life, and teeth possessing roots, removed from the skull after death. As such, teeth may behave differently in fluvial systems due to their differences in shape. In order to determine the influence of fluvial processes on the preservation and distribution of shed and root-bearing dinosaur teeth, the hydrodynamic behaviors of high-density urethane resin casts of shed and root-bearing Allosaurus and Camarasaurus teeth were experimentally tested for relative transport distances at increasing flow velocities in an artificial fluviatile environment. Results show that tooth cast specimens exhibited comparable patterns of transport at lower velocities, though the shed Camarasaurus teeth transported considerably farther in medium to higher flow velocities. Two-Way ANOVA tests indicate significant differences in the mean transport distances of tooth casts oriented perpendicular to flow (p < 0.05) with varying tooth morphologies and flow velocities. The differences exhibited in the transportability of shed and root-bearing teeth has important implications for taphonomic reconstructions, as well as future studies on dinosaur population dynamics, paleoecology, and feeding behaviors. Subjects Paleontology Peterson JE, Bigalke CL. 2013. Hydrodynamic behaviors of pachycephalosaurid domes in controlled fluvial settings: a case study in experimental dinosaur taphonomy. Palaios 28(5):285-292 DOI 10.2110/palo.2013.p13-003r. Peterson JE, Scherer RP, Huffman KM. 2011. Methods of microvertebrate sampling and their influences on taphonomic interpretations. Palaios 26:81-88 DOI 10.2110/palo.2010.p10-080r. Roach BT, Brinkman DL. 2007. A reevaluation of cooperative pack hunting and gregariousness in Deinonychus antirrhopus and other nonavian theropod dinosaurs.

Taphonomy, Second Edition, Nov 2010

There is no doubt among paleontologists that the fossil record of terrestrial vertebrates is frag... more There is no doubt among paleontologists that the fossil record of terrestrial vertebrates is fragmented and unevenly distributed
over space and time. The underlying causes of this patchiness derive from a combination of factors occurring before and after
the deposition of vertebrate remains. Large-scale vertebrate fossil distribution patterns present challenges in addressing
the effects of small-scale taphonomic processes on distribution patterns, and what, if any, effect they may have on biodiversity
reconstructions. This chapter presents a hierarchical model connecting small-scale taphonomic processes and large-scale fossil
preservation patterns. Factors acting at higher levels in the hierarchy constrain the range of taphonomic processes acting
at lower levels, whereas lower level processes are responsible for determining vertebrate preservation and the resulting fossil
record for an area. Secular changes in climate, tectonics, sea-level, etc. alter the distribution of both environments and
biodiversity over time. These changes in turn may alter the congruence between standing biodiversity and the fraction of that
diversity faithfully represented in the fossil record, skewing our understanding of extinct vertebrate ecosystems and their
evolution over time.

Background: There have been numerous studies on dinosaur biogeographic distribution patterns. How... more Background: There have been numerous studies on dinosaur biogeographic distribution patterns. However, these distribution data have not yet been applied to ecological questions. Ecological studies of dinosaurs have tended to focus on reconstructing individual taxa, usually through comparisons to modern analogs. Fewer studies have sought to determine if the ecological structure of fossil assemblages is preserved and, if so, how dinosaur communities varied. Climate is a major component driving differences between communities. If the ecological structure of a fossil locality is preserved, we expect that dinosaur assemblages from similar environments will share a similar ecological structure.

Our understanding of the complex faunal transitions taking place through the Early to Late Cretac... more Our understanding of the complex faunal transitions taking place through the Early to Late Cretaceous interval in North America is critical in reconstructing the complex biogeographic and evolutionary forces that drove the reorganization of Late Cretaceous terrestrial ecosystems. However, this record is based almost exclusively on fossil deposits from Laramidia, on the western side of the Interior Seaway. Little is known about faunal dynamics on the eastern landmass of Appalachia, especially during the early Late Cretaceous. The Woodbine Formation of north-central Texas was deposited during the middle Cenomanian (95-100 mya) and represents a coastal delta ecosystem. Knowledge of the Woodbine ecosystem has been greatly expanded with the recent discovery of the Arlington Archosaur Site (AAS), which preserves an extraordinarily diverse assemblage of dinosaurs, crocodyliforms, turtles, mammals, amphibians, chondrichthyans, osteichthyans, and plants. Sedimentary data suggest a strongly seasonal climate with a monsoonal wet season followed by a pronounced dry season that experienced periodic wildfires. When combined with previously described Woodbine taxa a picture emerges of a distinct transitional fauna characterized by Early Cretaceous groups including derived allosauroids, nodosaurid ankylosaurs, neosuchian crocodyliforms, and basal cryptodiran turtles mixed with early representatives of Late Cretaceous communities such as basal hadrosauroids, dromaeosaurids, troodontids, eusuchian crocodyliforms, and baenid and trionychoid turtles. Overall the Woodbine is similar in taxonomic composition to equivalent Laramidian deposits, yet share few genera in common supporting a widespread distribution of these groups prior to formation of the Interior Seaway. The Woodbine Formation shows the faunal transition in North America was an ongoing, gradual process that continued throughout the Cenomanian. This suggests that the characteristic Late Cretaceous communities assembled slowly, possibly representing a previously unrecognized community structure unique to this interval, and do not represent a rapid turnover event.

3D technology has great potential for distributing virtual fossils among specialists and the publ... more 3D technology has great potential for distributing virtual fossils among specialists and the public. Although technical hurdles for sharing 3D models are no longer significant, a sustained, stable platform for sharing paleontological 3D models with the scientific community and the public has yet to emerge. Researchers and museums are mutual stakeholders in open data distribution efforts. Any successful database will meet unique paleontological metadata needs, as well as accommodate institutional requirements for sensitive locality information and intellectual property. Digital 3D models have the potential to provide authentic educational experiences to many more students than would be possible with physical specimens. If widely distributed, they may also undercut the market in fossils and antiquities. This will be an open discussion of current efforts to create online vertebrate paleontology 3D databases, and will explore requirements for successful sharing of digital 3D data.