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Background Paretic propulsion [measured as anteriorly-directed ground reaction forces (AGRF)] and trailing limb angle (TLA) show robust inter-relationships, and represent two key modifiable post-stroke gait variables that have biomechanical and clinical relevance. Our recent work demonstrated that real-time biofeedback is a feasible paradigm for modulating AGRF and TLA in able-bodied participants. However, the effects of TLA biofeedback on gait biomechanics of post-stroke individuals are poorly understood. Thus, our objective was to investigate the effects of unilateral, real-time, audiovisual TLA versus AGRF biofeedback on gait biomechanics in post-stroke individuals. Methods Nine post-stroke individuals (6 males, age 63 ± 9.8 years, 44.9 months post-stroke) participated in a single session of gait analysis comprised of three types of walking trials: no biofeedback, AGRF biofeedback, and TLA biofeedback. Biofeedback unilaterally targeted deficits on the paretic limb. Dependent variables included peak AGRF, TLA, and ankle plantarflexor moment. One-way repeated measures ANOVA with Bonferroni-corrected post-hoc comparisons were conducted to detect the effect of biofeedback on gait biomechanics variables. Results Compared to no-biofeedback, both AGRF and TLA biofeedback induced unilateral increases in paretic AGRF. TLA biofeedback induced significantly larger increases in paretic TLA than AGRF biofeedback. AGRF biofeedback increased ankle moment, and both feedback conditions increased non-paretic step length. Both types of biofeedback specifically targeted the paretic limb without inducing changes in the non-paretic limb. Conclusions By showing comparable increases in paretic limb gait biomechanics in response to both TLA and AGRF biofeedback, our novel findings provide the rationale and feasibility of paretic TLA as a gait biofeedback target for post-stroke individuals. Additionally, our results provide preliminary insights into divergent biomechanical mechanisms underlying improvements in post-stroke gait induced by these two biofeedback targets. We lay the groundwork for future investigations incorporating greater dosages and longer-term therapeutic effects of TLA biofeedback as a stroke gait rehabilitation strategy. Trial registration NCT03466372

Obruchevodid petalodonts are rare small chondrichthyans known from nearly complete to partial skeletons from the Upper Mississippian (Serpukhovian) Bear Gulch Limestone of central Montana and isolated teeth from the Upper Mississippian Bangor Limestone of northern Alabama. New records of obruchevodid petalodonts are presented here from the Middle Mississippian (Viséan) Joppa Member of the Ste. Genevieve Formation at Mammoth Cave National Park, Kentucky. Obruchevodids are here represented by multiple teeth of a new taxon, Clavusodens mcginnisi n. gen. n. sp., and a single tooth referred to ?Netsepoye sp. Clavusodens mcginnisi n. gen. n. sp. is characterized by teeth with pointed mesiodistal and lingual margins and more robust chisel-like cusps on the anterolateral and distolateral teeth. The suggestion that obruchevodid petalodonts evolved to inhabit complex reef-like environments and other nearshore habitats with a feeding ecology analogous to extant triggerfish is explored and discussed. New records of two species of obruchevodid petalodont chondrichthyans are described from the Middle Mississippian Joppa Member of the Ste. Genevieve Formation from Mammoth Cave National Park, Kentucky. The two species are Clavusodens mcginnisi new genus new species, which had more robust crushing-type teeth for its kind, and ?Netsepoye sp., which is based on a partial tooth. These two records represent the oldest known obruchevodid petalodonts, which previously were known from younger Mississippian-age rocks in Montana and Alabama. Obruchevodid petalodonts were among the most specialized cartilaginous fishes during the Mississippian, potentially adapted to live in complex reef and reef-like habitats.

Footprint evidence of human-megafauna interactions remains extremely rare in the archaeological and palaeontological records. Recent work suggests ancient playa environments may hold such evidence, though the prints may not be visible. These so-called “ghost tracks” comprise a rich archive of biomechanical and behavioral data that remains mostly unexplored. Here we present evidence for the successful detection and 3-D imaging of such footprints via ground-penetrating radar (GPR), including co-associated mammoth and human prints. Using GPR we have found that track density and faunal diversity may be much greater than realized by the unaided human eye. Our data further suggests that detectable subsurface consolidation below mammoth tracks correlates with typical plantar pressure patterns from extant elephants. This opens future potential for more sophisticated biomechanical studies on the footprints of other extinct land vertebrates. Our approach allows rapid detection and documentation of footprints while enhancing the data available from these fossil archives.

Theodore Roosevelt National Park (THRO) in western North Dakota comprises badlands that surround the Little Missouri River in three separate units. Established initially as a national memorial park in 1947 and redesignated as a national park with its current boundaries in 1978, THRO was founded for its connection to its namesake, the United States president, and continues to memorialize Roosevelt’s ideals of stewardship with its management of its diverse cultural and natural resources. The badlands in the park expose the highly fossiliferous Paleocene-age Bullion Creek and Sentinel Butte Formations that have been investigated extensively outside of the park’s boundaries but not as much within them. Following a survey between 1994 and 1996 and later paleontological discoveries in the park, a Paleontological Resource Inventory was conducted during 2020 and 2021 to gauge these resources within THRO and determine best management and protection practices. This inventory was put to the test in monitoring for fossil resources preceding two road construction projects in the park: on the South Loop Road in 2021 and the Buck Hill Road in 2023. The inventory gave information as to what paleontological resources were to be encountered during construction, including known fossil occurrences and localities within and surrounding the project area. Results of monitoring included the discovery of new paleontological material, including bird material and well-preserved angiosperm fossils around the South Loop Road, and a potentially high-yield vertebrate site including choristodere (an extinct aquatic reptile), bowfin, and turtle material near Buck Hill Road. These instances demonstrate the importance paleontological resource inventories as a foundation for resource monitoring preceding construction projects.

George Washington Birthplace National Monument (GEWA) is a National Park Service (NPS) unit located in the Northern Neck of Virginia, situated on low bluffs overlooking the Potomac River. This small park unit, focused primarily on cultural and historical resources, may seem at first glance to be an unlikely candidate for notable paleontological resources. However, the bluffs are composed in large part of the fossiliferous early–middle Miocene-age Calvert Formation, and these bluffs and the adjacent shoreline have long been known by locals and rockhounds as places to find fossil shark teeth and other fossils. Following initial contact in the late 1990s and early 2000s, the NPS Paleontology Program has worked closely with GEWA since 2014 on the dual aims of stemming illegal fossil collecting and monitoring non-renewable paleontological resources in the face of rising river levels, increasing storms, and other effects of climate change. The working relationship is a case study for managing fossil resources facing similar challenges. Fossil theft has declined since the project began, as measured by decreasing bluff vandalism left by fossil removal. The benefits of establishing and maintaining a close relationship with park staff are superbly illustrated by the March 2020 recovery of two specimens of Miocene dolphins at imminent risk of loss to wave erosion or unauthorized collection. Plans are in progress to expand this collaborative work with the help of regional institutions.

The history associated with the discovery, research, preservation, protection, and loss of the fossil cycadeoid locality near Minnekahta in the southern Black Hills of South Dakota—which for 35 years was designated as Fossil Cycad National Monument—has gained considerable public attention. Several publications have attempted to capture portions of this history through the assimilation of information from archives, reports, correspondence, photographs, and other records associated with the monument. Previously unknown records continue to emerge, helping to expand and reshape the understanding of the monument’s unfortunate history, and also raising new questions. Some of the newly uncovered information is presented here. Additionally, several questions are identified that hopefully might be advanced through communication with individuals who are able to share additional information or historical records to fill in some of the gaps related to the history of Fossil Cycad National Monument.

Paleontological site monitoring in National Park Service units can deviate from the recommended cyclical protocol because of unique challenges each unit may face. These challenges include staffing limitations or turnover, difficulty accessing remote sites, and high work volume. Insufficient monitoring of fossil sites might result in the loss of knowledge or data due to degradation or loss of resources. New monitoring protocols were tested at the Copper Canyon ichnofossil locality in Death Valley National Park (DEVA) to address the highlighted management challenges. The monitoring protocol presented here was designed to be streamlined and simple, to be utilized by paleontologists and non-paleontologists alike, and to overcome challenges, thereby, improving undermanaged sites. The monitoring protocol included baseline evaluation and imaging of the 78 track localities within Copper Canyon. Each site was assigned a sensitivity status; identifying its recommended monitoring cyclicity of high, moderate, or low. It was determined that monitors could take as few as two field trips to Copper Canyon per year and monitor between five to ten sites each trip. This could be accomplished by DEVA’s resources management, interpretation, or law enforcement staff, or a volunteer. Monitors use a portable device, pre-loaded with site-specific paleontological data, to interactively record changes at a site and complete a short seven question form with their observations. Data are stored on the device and later transferred to a central paleontological database. Through this protocol, DEVA can utilize a community-based approach to better manage fossil resources, one which could be replicated by other National Park Service units that grapple with similar monitoring challenges.

Globally, caves provide important refugia for bats. The Grand Canyon, more than 400 km (250 mi) long, consists of steep-sided, rocky formations with hundreds to thousands of natural caves. Two of these, Double Bopper and Leandras Caves, are remarkable because of the presence of desiccated bat carcasses, ranging in condition from skeletal to well-preserved animals identifiable to species. Both caves are complex but differ in length and structure. Double Bopper Cave, >60 km (37 mi) long, is variable with narrow passages. Leandras Cave, 24 km (15 mi) long, has wide, open passages. We surveyed both caves, collecting information for 482 specimens. We initially hypothesized that a single catastrophic event caused the deaths of many individuals or that bats died of various causes over a long period. We expected bat communities to differ between caves, since different cave structures would favor different species based on flight maneuverability. Radiocarbon dating of 67 samples found ages ranged from modern to >45,800 cal BP, spanning the Last Glacial Maximum. The dominant bat species in each cave differed, with Townsend’s big-eared bat (Corynorhinus townsendii), a cave obligate, dominant in Double Bopper Cave and silver-haired bat (Lasionycteris noctivagans) dominant in Leandras Cave. Bats continue to use these caves today, as evidenced by the presence of fresh guano. The remarkable evidence of long-term continuous use of these caves by bats illustrates the importance of protection and conservation to provide habitat for them. The caves also provide an unprecedented time machine to study bat communities from the past, understand long-term patterns of habitat use, and prepare for climate change.

The fossil record preserved throughout the National Park Service spans more than a billion years and is documented in at least 267 park units. The discovery, collection, study, and resource management of fossils from localities which are currently within parks sometimes predate the establishment of the National Park Service and many of the parks. Public education and interpretation at parks such as Agate Fossil Beds and Tule Springs Fossil Beds national monuments and many other designated areas include information on the rich history of paleontological field work by notable paleontologists undertaken prior to the areas being preserved as national park areas. Another important historical aspect for several dozen parks involves the conservation efforts undertaken by the public and interest groups to preserve and protect these important fossil localities. The evolution of the science and methodologies in paleontology is reflected in the resource management undertaken by the National Park Service and documented in park resource management records and archives, scientific publications, and agency policy. Today the National Park Service celebrates fossils by coordinating the National Fossil Day partnership which helps to promote the scientific and educational value of fossils.

In recent years the discovery of paleontological and archaeological resources exposed because of natural disasters and rapid erosion—mostly linked to climate change—has occurred at a phenomenal rate. Each year wildfires, floods, landsides, retreating glaciers, snow melt, soil erosion, and receding lakes and reservoirs are uncovering valuable resources. Unfortunately, these same forces often lead to the loss of these resources before they can be preserved or documented. At White Sands National Park, as moisture within the soil is being reduced by persistent droughts and rising temperatures, 23,000-year-old fossil prints of people and Ice Age megafauna are being exposed—and then rapidly lost to soil erosion. Consequently, there is an urgent need to document the fossil prints before the record is lost. This is a concern not only for White Sands, but also for dry lake beds throughout the Southwest and around the world where fossil prints may not have yet been discovered but are rapidly being lost. At White Sands, we are working with an impressive team of experts to develop techniques to rapidly document these resources. The fossil resources at White Sands provides an important analogue for understanding other pluvial systems throughout the world.