Stephen T. Hasiotis

A comparison of crayfish burrow morphologies: Triassic and Holocene fossil, paleo‐ and neo‐ichnological evidence, and the identification of their burrowing signatures

The architectural and surficial morphologies of crayfish burrows from the Upper Triassic Chinle Formation and Holocene sediments were compared in order to determine: 1) if Triassic burrows could truly be attributed to crayfish activity; 2) how comparable the burrowing mechanisms are; and 3) whether or not a common set of burrowing signatures could be identified for both ancient and modern freshwater crayfish. Materials used in this study include burrows from the members of the Upper Triassic Chinle Formation, casts of modern burrows constructed by Procambarus clarkii Hobbs and Procambarus acutus acutus (Girard) in the laboratory, and casts of naturally constructed modern burrows of Cambarus diogenes di‐ogenes (Girard). Triassic and Holocene crayfish burrow morphologies exhibit simple to complex architectures, varying degrees of branching, chamber, and chimney development. They also exhibit relatively textured surficial morphologies (bioglyphs) such as scrape and scratch marks, mud‐ and lag‐liners, knobby ...

Complex ichnofossils of solitary and social soil organisms: understanding their evolution and roles in terrestrial paleoecosystems

Abstract The range of extant nest architectures for different types of solitary to social insects as well as the key features in their architecture has assisted in the identification of their structures in the geologic record. The recognition and interpretation of complex ichnofossils as the product of insects that indicate varying degrees of sociality represents a major development in the study of continental ichnology. Complex ichnofossils constructed since the Mesozoic by termites (Isoptera), bees (Hymenoptera: Apoidea), wasps (Hymenoptera: Apoidea and Vespoidea), and ants (Hymenoptera: Formicidae) represent unique solutions through degrees of social cooperation to the problems of fossorial life in terrestrial environments. Other such trace-making organisms as various types of beetles and vertebrates also construct a range of simple to complex burrows that indicate solitary, subsocial, and gregarious behaviors. Burrows of vertebrates result from relative degrees of social behavior that are unlike those of social insects. Complex ichnofossils are highly variable in architecture and indicate the type of organism, the number of individuals per nest, the length of time the structure was used, the degree of sociality, and, in some cases, the amount of time the substrate has been exposed to surface processes. A pattern of interconnected structures of varying length, width, height, and number usually distinguishes complex traces. Nests of insect societies have the greatest variability in ichnofossil complexity – being simple to extremely elaborate structures. These traces also preserve major innovations in soil ecosystems that include food hoarding, adaptations to disturbance from flooding and precipitation, enduring unpredictable hypercapnic and hypoxic conditions, and reproductive strategies by employing a subterranean, hemimetabolous or holometabolous life cycle. Polychresichnia is proposed for trace fossils that were involved in many simultaneous, multiple behaviors and uses. Aedificichnia and calichnia could likely be subsets of polychresichnia because many of the ichnofossil nests originally included in those categories were protected by the adults during brood rearing, used as living and sleeping quarters for the adults, and used as shelter from adverse weather. Nest architecture is an important source of information on the evolution of behavior of social insects as well as for other social organisms. Many of the organisms mentioned here have trace-fossil records that extend to the earliest Mesozoic and predate their earliest body-fossil records in the Cretaceous. Most of these trace fossils have changed remarkably little in 225 million years, indicating evolutionary stasis of the basic building blocks in nest construction.

Naktodemasis bowni: New Ichnogenus and Ichnospecies for Adhesive Meniscate Burrows (AMB), and Paleoenvironmental Implications, Paleogene Willwood Formation, Bighorn Basin, Wyoming

Abstract Adhesive meniscate burrows (AMB) are common in alluvial paleosols of the Paleogene Willwood Formation, Bighorn Basin, Wyoming. AMB are sinuous, variably oriented burrows composed of a nested series of distinct, ellipsoidal packets containing thin, tightly spaced menisci subparallel to the bounding packet. Menisci are non-pelleted and texturally homogeneous with each other and the surrounding matrix. AMB were constructed most likely by burrower bugs (Hemiptera: Cydnidae), cicada nymphs (Hemiptera: Cicadae), and less likely by scarabaeid (Coleoptera: Scarabaeidae) or carabid beetles (Coleoptera: Carabidae), based on burrow morphology and comparison to similar structures produced by these organisms in modern soils. Extant burrowing insects excavate backfilled burrows in well-rooted A and upper B horizons of soils generally below field capacity depending on soil type. This study demonstrates that AMB are distinct morphologically from such previously described ichnofossils as Beaconites, Laminites, Scoyenia, Taenidium, and Ancorichnus. Naktodemasis bowni, a new ichnogenus and ichnospecies, represents burrows composed of nested ellipsoidal packets backfilled with thin, tightly spaced, menisci subparallel to the bounding packet. The presence of N. bowni indicate periods of subaerial exposure associated with pedogenic modification under moderately to well-drained soil conditions, or during periods of better drainage in imperfectly drained soils. N. bowni, therefore, can differentiate alluvial paleoenvironments from marine and lacustrine paleoenvironments, as well as periods of subaerial exposure of sediments deposited in aquatic settings.

Application of morphologic burrow interpretations to discern continental burrow architects: Lungfish or crayfish?

A methodology for trace fossil identification using burrowing signatures is tested by evaluating ancient and modern lungfish and crayfish burrows and comparing them to previously undescribed burrows in a stratigraphic interval thought to contain both lungfish and crayfish burrows. Permian burrows that bear skeletal remains of the lungfish Gnathorhiza, from museum collections, were evaluated to identify unique burrow morphologies that could be used to distinguish lungfish from crayfish burrows when fossil remains are absent. The lungfish burrows were evaluated for details of the burrowing mechanism preserved in the burrow morphologies together forming burrowing signatures and were compared to new burrows in the Chinle Formation of western Colorado to test the methodology of using burrow signatures to identify unknown burrows. Permian lungfish aestivation burrows show simple, nearly vertical, unbranched architectures and relatively smooth surficial morphologies with characteristic quasi‐horizontal striae on...

Vertebrate Burrows from Triassic and Jurassic Continental Deposits of North America and Antarctica: Their Paleoenvironmental and Paleoecological Significance

Comparisons of recently identified Triassic and Jurassic continental trace fossils in North America and Antarctica to modern mammal and reptilian burrows facilitate the identification and interpretation of the ancient burrows as vertebrate in origin, indicating advanced behaviors. Hollow, bowl-shaped depressions in the Petrified Forest Member of the Upper Triassic Chinle Formation in Petrified Forest National Park, Arizona, are interpreted as nest-holes constructed possibly by phytosaurs, aeotosaurs, turtles, or rauisuchians. Large-diameter, multiple-branching, and interconnected burrows in the Owl Rock Member of the Chinle Formation in southeastern Utah are tentatively interpreted as vertebrate burrows indicating communal behavior. Complex, large-diameter burrows in the Salt Wash Member of the Upper Jurassic Morrison Formation near the Henry Mountains in southern Utah are interpreted as burrow systems of fossorial mammals. Large-diameter, gently dipping, simple, subhorizontal burrows in the Salt Wash Member are interpreted as possible dwelling burrows of sphenodontids. Other vertebrate trace fossils, such as the large-diameter burrows from the Lower Triassic Fremouw Formation in the Queen Maud Mountains of Antarctica, are reinterpreted as vertebrate burrows and were likely constructed by small mammal-like reptiles. These burrows were thought to have been enigmatic in origin and different from very large-diameter burrows interpreted as therapsid dwelling burrows. Descriptions and interpretations of all these trace fossils are important because most vertebrate ichnology research to date has focused on trackways or locomotion experiments with modern reptiles and birds. These Triassic and Jurassic ichnofossils represent fossorial and nesting behavior of several different groups of vertebrates. The Fremouw Formation burrows indicate fossorial behavior in several sizes of vertebrates, including small and large therapsids. The burrows were likely used for shelter, giving birth, raising young, and hibernation. During the early Mesozoic, the Fremouw landscapes were thought to have had cold winters due to their high-paleolatitude position. The bowl-shaped depressions from the Petrified Forest Member of the Chinle Formation likely represent the earliest known structures excavated by reptilians for the sole purpose of reproduction. Basic nest-hole architecture in extant reptiles with early Mesozoic ancestry has changed minimally in nearly 220 million years. Large-diameter, multiple branching, and interconnected burrows in the Owl Rock Member of the Chinle Formation were likely constructed by fossorial vertebrates that had communal family groups. Simple, gently dipping, subhorizontal burrows in the Morrison Formation were used by crocodiles or sphenodontids as dwelling structures constructed in firm, subaerially exposed substrata close to open bodies of water. Complex, large-diameter burrows in the Salt Wash Member suggest subsocial behavior of fossorial mammals, where the burrow was used for raising young, storage and disposal of food and wastes, and coping with episodic water inundation. Research demonstrates that fossorial behavior of reptiles, therapsids, and mammals was established by the beginning of the Mesozoic and prior to the break-up of Pangea. The basic architecture of vertebrate nest construction has changed little in nearly 280 million years. Fossorial burrowing behavior likely evolved several times in different vertebrate groups during this time. These basic burrow architectures are also used by invertebrate groups. This overlap in burrow architectures between vertebrates and invertebrates suggests strongly that paleoenvironmental and paleoclimatic organism-substrate relationships dictate the architecture used by the organism. These burrow morphologies indicate particular physicochemical conditions in terrestrial and freshwater settings that are unique to the continental realm.

Termite (Insecta: Isoptera) nest ichnofossils from the upper triassic chinle formation, petrified forest national park, Arizona

A fossil nest (calie), including chambers and galleries (runaways), from the lower part of the Petrified Forest Member of the Upper Triassic Chinle Formation in Petrified Forest National Park, Arizona, is similar to nests constructed by modern primitive termites (Insecta: Isoptera), which reflect cooperation in nest construction typical of complex social behavior. A new ichnogenus and ichno‐species, Archeoentomichnus metapolypholeos, is proposed for the distinctive ichnofossil that may represent the efforts of a social caste system in primitive termites. The Late Triassic (Late Carnian) nest also may represent the earliest known fossil evidence of Isoptera (termites) and is suggestive of the antiquity of social behavior among insects. Social behavior in insects, including termites, was previously thought to have evolved in the Early Cretaceous in conjunction with the evolutionary radiation of angiosperms. Because the fossil and ichnofossil record of insects and organisms suggested to be insects dates back...

Application of forensic science techniques to trace fossils on dinosaur bones from a quarry in the Upper Jurassic Morrison Formation, northeastern Wyoming

Abstract Trace fossils on sauropod skeletons from a quarry in fluvial deposits of the Morrison Formation, Wyoming, are used to reconstruct the taphonomic history of the dinosaur bone accumulation. Shallow pits; rosettes; hemispherical pits; thin, curvilinear, branching grooves; and U- to V-shaped linear grooves make up trace fossils found on sauropod skeletons. The traces were interpreted by comparisons to traces on modern bone. Rosettes are circular rings of modified bone and are likely an early stage in the production of shallow pits. They are interpreted as pupation chambers constructed in dried flesh in contact with sauropod bone. Hemispherical pits are circular with a U-shaped cross section and interpreted as dermestid pupation chambers completed in sauropod bone. Thin, curvilinear, branching grooves are semicircular in cross section, form irregular dendritic or looping patterns, and are interpreted as root etchings. U- to V-shaped linear grooves are interpreted as theropod or crocodilian bite marks. Skeletal articulation and condition and distribution of bone modification traces suggest the skeletons accumulated at this site over no more than 3.5 years, with the bulk of the skeletons contributed during the dry season in the final 3–6 months. Carcasses went through all stages of decomposition—including the dry stage, represented by shallow pits, rosettes, and hemispherical pits. Vertebrate scavengers and necrophagous arthropods fed on the carcasses during all decomposition stages prior to burial of the assemblage.

Traces and burrowing behaviors of the cicada nymph Cicadetta calliope: Neoichnology and paleoecological significance of extant soil-dwelling insects

Abstract This study documents the traces and burrowing behaviors of nymphs of the prairie cicada Cicadetta calliope (Hemiptera: Cicadidae), as observed in neoichnological experiments. Cicada nymphs were collected from the C horizons of sandy Fluvents along the Kansas River east of Lawrence, Kansas. The nymphs appeared to be fifth instars, 13–17 mm long and 6–7 mm wide. Nymphs were placed in plastic enclosures containing layers of colored, moist, very fine-grained sand. They burrowed immediately, excavating air-filled, sediment-enclosed cells between 20 mm and 40 mm long and averaging 9 mm wide. Burrowing was completed in three stages: (1) sediment in the forward portion of the cell was excavated and rolled into a ball with the forelimbs; (2) the nymph turned 180° using a forward roll, and moved to the back of the cell; and (3) the sediment ball was pushed up against the back wall of the cell and kneaded with the forelimbs into a thin layer. Resulting burrow traces are sinuous and distinctly meniscate and demonstrate that insect larvae construct meniscate, backfilled burrows in well-drained terrestrial settings. Cicadetta calliope nymphs and their traces are excellent analogs for meniscate trace fossils commonly found in late Paleozoic–Cenozoic alluvial deposits and paleosols. Such meniscate trace fossils are useful for interpreting the paleoenvironment and paleohydrogeology of the units in which they are found. In addition, such backfilled burrows can be used to supplement the fossil record of cicada-like hemipterans, currently known only from the latest Permian to the Early Triassic.

The Trace-Fossil Record of Vertebrates

SUMMARY: The trace-fossil record of vertebrates contains behavioral evidence of fish, amphibians, reptiles, dinosaurs, mammals, and birds in continental, transitional, and marine paleoenvironments since the Devonian. The study of vertebrate trace fossils includes tracks, trails, burrows, nests, and such feeding traces as bite marks, coprolites, gastroliths, and regurgitalites. Behaviors recorded by these traces include various kinds of (1) locomotion, (2) dwelling, (3) aestivation, (4) breeding and nesting, as well as (5) acts of feeding, which also result in (6) digestion, (7) regurgitation, and (8) defecation. These trace fossils represent the interaction between a vertebrate and a medium, which includes softgrounds, firmgrounds, hardgrounds, plants, and other animals. Humans also have a trace-fossil record, and, like other vertebrates, produce numerous trace fossils that result from different kinds of behavior.

Continental Ichnology: Fundamental Processes and Controls on Trace Fossil Distribution

SUMMARY: Continental biota are related to sediment through feeding, dwelling, locomotion, reproduction, and searching behavior evident as tracks, trails, burrows, nests of animals, and rooting patterns of plants. Such vestiges are preserved in the geologic record as trace fossils. The lateral and vertical distribution of modern trace-making organisms within an environment is controlled by sediment characteristics, soil moisture, water-table levels, ecological associations, and more. Trace fossils in the geologic record can be used to interpret the palaeoenvironmental, palaeoecologic, palaeohydrologic, and palaeoclimatic settings because a well-defined relationship exists between climate, hydrology, soils, environment, and all biodiversity. Trace fossils also relate information about soil formation and development, the type of biologic activity, topography of the landscape and its relationship to groundwater profile, and duration of time that a body of sediment has been stable at the surface with respect to sedimentation rate. Thus, trace fossils in the continental realm are proxies for: (1) biodiversity in terrestrial and aquatic palaeoenvironments not recorded by body fossils; (2) above- and below-ground palaeoecological associations; (3) palaeosol formation; (4) palaeohydrology and palaeo-groundwater profiles; and (5) seasonal and annual palaeoclimate indicators and climate change.