Antler Formation Research Articles

Variation in stable carbon (δ13C) and nitrogen (δ15N) isotope compositions along antlers of Qamanirjuaq caribou (Rangifer tarandus groenlandicus).

Annual antler growth begins in the spring and is completed by late summer for male caribou (Rangifer tarandus groenlandicus) from the Qamanirjuaq herd (Nunavut, Canada), aligned with both the spring migration and a seasonal dietary shift. Antlers may provide a non-lethal means of studying short- and long-term changes in caribou ecology through incorporated isotopes of carbon (δ13C) and nitrogen (δ15N). We sampled the antlers of 12 male caribou from the Qamanirjuaq herd culled in September 1967. We predicted that serial sampling of antlers would reflect the known seasonal dietary change from lichen to grass-like and shrub diet based on rumen contents from individuals culled during the same period. The δ13C and δ15N were analyzed in food sources and every 3 cm along each antler's length. The carbon isotope compositions of collagen (δ13Ccol) varied by ~0.5‰ among individuals and within antlers, while the carbon isotope compositions of antler bioapatite (δ13CCO3) increased by 1-1.5‰ from pedicle to tip. Values of δ15Ncol increased within antlers by 1-3‰ from pedicle to tip and varied by 3‰ among the individuals sampled. Antler collagen was lower in δ15Ncol by ~1‰ relative to bone collagen. Bayesian mixing models were conducted to test for changes in dietary proportions from antler isotope compositions. Mixing models did not indicate significant dietary shifts for any individual during antler formation, showing consistently mixed diets of fungi, horsetail, lichen, and woody plants. Increases in δ15Ncol in antler tissue could, therefore, correspond to subtle seasonal dietary changes and/or the physiological stress of antler tissue development.

Wing phalanges of a ?thalassodromine pterosaur from the Aptian–Albian Antlers Formation of Texas, USA

Fragmentary pterosaurian wing phalanges from the Aptian-Albian Antlers Formation of north-central Texas, USA are described. Wing phalanges 1 and 2 have suboval shafts with thickened bone at the leading and trailing edges, whereas the third wing phalanx has a flattened airfoil-like cross-section with greatly thickened bone at the leading and trailing edges and a small subrectangular medullary cavity. The cortical bone exhibits an unusual coarse surface texture, and bone thin sections reveal extensive Haversian remodeling and endosteal lamellar bone. The morphology of the wing phalanges differs from that of dsungaripterids, pteranodontoids, and azhdarchids, so the specimen is not a North American record of the Dsungaripteridae as some have stated; whereas based on comparisons to a roughly contemporaneous indeterminate thalassodromine pterosaur specimen from the Romualdo Formation of Brazil, the specimen is tentatively interpreted as an indeterminate thalassodromine with an estimated wingspan of ∼3.5 m.

A simple method for effective cryopreservation of antlerogenic periosteum of sika deer.

Antlerogenic periosteum (AP) is the unique tissue type that gives rise to antlers and their antecedents, the pedicles. Deer antlers are the only mammalian organ that can fully regenerate. Efficient investigation of the mechanism of antler formation and regeneration requires year-round availability of AP, but naturally AP can only be obtained less than two months in a year. In the present study we took the cryopreservation approach to store the sampled AP in ultra-low temperature to overcome the limited period of availability. First, we evaluated the suitability of vitrification and cell cryopreservation method for cryopreservation of AP, cell migration status of the AP tissue pieces confirmed that vitrification methods did not work as the only few AP cells migrated out, whereas migrated cell numbers in the cell-cryo group (conventional method for cryopreservation of cells) were comparable to those of the fresh AP group. To further evaluate the suitability of cell cryopreservation method for AP tissue, AP samples were allocated into three groups based on the different ratios of cryopreservation reagents (dimethyl sulfoxide [DMSO], dulbecco's modified eagle's medium [DMEM] and fetal bovine serum [FBS]): AP-Cell-1 (1:4:5), AP-Cell-2 (1:2:7) and AP-Cell-3 (1:0:9), the results showed that migrated cell number were again comparable to the fresh AP group. There was no significant difference between the cell-cryo groups (AP-Cell-1 and AP-Cell-3) and the fresh group: (1) in viability (p > 0.05) through trypan blue staining (91.2%, 90.8%, and 92.4%, respectively); (2) in the attachment day, and all on Day 5 after cell seeding; (3) in cell proliferation rate (p > 0.05) through Cell Counting kit 8 (CCK8) measurement; and (4) in number of the formed clones (Clonogenicity). In the in vivo trials, there was no visible difference in temporal differentiation sequence of the formed xenogeneic antlers between the fresh AP and cryopreserved AP (AP-Cell-1 and AP-Cell-3). Overall, we found that the AP tissue was well cryopreserved just using the conventional freezing and thawing methods for cells, and their viability and developmental potential comparable to the fresh AP both in vitro and in vivo. The long-term preservation of the AP tissue is of great significance for the study of the periosteum biology in general and the mechanism underlying xenogeneic generation and regeneration of deer antlers in specific.

Vertebrate paleontology of the Cloverly Formation (Lower Cretaceous), III: a new species of Albanerpeton, with biogeographic and paleoecological implications

ABSTRACT We describe a new species of the albanerpetontid amphibian Albanerpeton from three localities in the Lower Cretaceous Cloverly Formation of Wyoming, U.S.A. Radiometric dates between ∼111–112 Ma indicate it is slightly younger than A. arthridion from the Antlers Formation. The new species is diagnosed on a pair of fused frontals that possess a unique combination of characters, mixing plesiomorphic features of the internasal process with a more derived overall shape and proportions. Referred material includes premaxillae, maxillae, dentaries, atlantes, ‘axes,’ trunk vertebrae, humeri, and an ilium. Phylogenetic analyses place the new species near the base of Albanerpeton sensu lato but without fully resolving its position. The inclusion of Shirerpeton and Wesserpeton within this clade opens up the possibility that these genera might be incorporated into Albanerpeton, or that a number of species formerly assigned to Albanerpeton might receive new generic assignments. By including several informal species in our analysis, it becomes clear that character distributions are more homoplastic and that past genus typologies are probably less secure. We assign the new species to Albanerpeton conservatively, pending further phylogenetic study. The Cloverly Albanerpeton is found in unambiguously aquatic deposits, suggesting that the animal lived near these settings for at least part of its life. This is a common habitat for Mesozoic albanerpetontids, unlike the karst-dominated, often drier, deposits in which Cenozoic species are typically found. Despite the recent discovery of a probable arboreal species, it is likely that albanerpetontids inhabited a range of habitats throughout their evolutionary history.

Antler stem cells and their potential in wound healing and bone regeneration.

Compared to other vertebrates, the regenerative capacity of appendages in mammals is very limited. Deer antlers are an exception and can fully regenerate annually in postnatal mammals. This process is initiated by the antler stem cells (AnSCs). AnSCs can be divided into three types: (1) Antlerogenic periosteum cells (for initial pedicle and first antler formation); (2) Pedicle periosteum cells (for annual antler regeneration); and (3) Reserve mesenchyme cells (RMCs) (for rapid antler growth). Previous studies have demonstrated that AnSCs express both classic mesenchymal stem cells (MSCs) and embryonic stem cells (ESCs), and are able to differentiate into multiple cell types in vitro. Thus, AnSCs were defined as MSCs, but with partial ESC attributes. Near-perfect generative wound healing can naturally occur in deer, and wound healing can be achieved by the direct injection of AnSCs or topical application of conditioned medium of AnSCs in rats. In addition, in rabbits, the use of both implants with AnSCs and cell-free preparations derived from AnSCs can stimulate osteogenesis and repair defects of bone. A more comprehensive understanding of AnSCs will lay the foundation for developing an effective clinical therapy for wound healing and bone repair.

Paleoenvironmental and paleoclimatic reconstruction of Cretaceous (Aptian-Cenomanian) terrestrial formations of Texas and Oklahoma using phyllosilicates

Clay mineralogy, chemistry, and stable oxygen and hydrogen-isotope compositions of 11 phyllosilicate samples from Cretaceous paleosol profiles were determined in order to evaluate Early-to-Late Cretaceous paleoenvironments and paleoclimates around north-central Texas and southern Oklahoma. Samples consist of mineralogical mixtures of illite, smectite, and kaolinite. Samples from the Albian Antlers Formation in southern Oklahoma and the Cenomanian Woodbine Formation are dominated by kaolinite, while the remaining samples are dominated by smectite and illite. Major element compositions of paleosol matrix materials are used to calculate CALMAG weathering values that range from 31 to 84 and correspond to Cretaceous paleoprecipitation estimates ranging from 270 to 1490 mm/yr. Paleosol phyllosilicate hydrogen and oxygen stable isotope values range from −50‰ to −67‰ to 18.5‰ to 21.7‰, respectively, and in conjunction with their respective mineral and chemical compositions, correspond to in-situ soil crystallization temperatures ranging from 26 ± 3 °C to 31 ± °C. Paleoprecipitation trends exhibit two marked increases in precipitation from the Early to Late Cretaceous, in the Albian Antlers Formation and Cenomanian Woodbine Formation. Stratigraphic intervals with phyllosilicates that yield cooler temperature estimates coincide with stratigraphic intervals with markedly higher precipitation estimates based on CALMAG values. Importantly, cool, high precipitation intervals correlate with periods of extensive shallow seas upon the North American craton. Comparison of Cretaceous temperature, precipitation and meteoric water estimates to modern analogs supports the presence of climates similar to modern tropical climates during the Cretaceous at subtropical or temperate paleolatitudes in what is now Texas and Oklahoma, consistent with general circulation models and energy balance models suggesting a pervading Cretaceous greenhouse.

Quantitative proteomics analysis of deer antlerogenic periosteal cells reveals potential bioactive factors in velvet antlers

Velvet antlers (VA) have been used as medicines and nutraceuticals for over 2000 years. Meanwhile, deer antlers are the only mammalian organs that can fully regenerate after annual shedding. The antler formation and regeneration rely on the stem cells resident in antlerogenic periosteum (AP), transplantation of which can induce ectopic antler formation. Here, a comprehensive quantitative proteomic analysis of antlerogenic periosteal cells (AP cells), compared with the adjacent facial periosteal cells (FP cells), was carried out, from both extracellular and intracellular perspectives. In this study, the stable isotope labeling by amino acids in cell culture (SILAC) was applied to ensure the precision of quantification. Then, the protein equalization strategy and reverse-phase liquid chromatography (RPLC) separation in high pH were utilized to improve the depth of proteome profiling. Proteomics analysis of the conditioned media (CM) from AP and FP cells showed that significantly over-expressed extracellular proteins in AP cells were involved in cell proliferation, angiogenesis and neurogenesis. Combining the extracellular and intracellular proteomes, we found several potential secreted proteins might regulate antler formation and regeneration, such as SFRP4 and LUM. These results provide new insight into the underlying mechanism of antler formation and regeneration.

First Documented Pathologies in Tenontosaurus tilletti with Comments on Infection in Non-Avian Dinosaurs

In 2001, a nearly complete sub-adult Tenontosaurus tilletti was collected from the Antlers Formation (Aptian-Albian) of southeastern Oklahoma. Beyond its exceptional preservation, computed tomography (CT) and physical examination revealed this specimen has five pathological elements with four of the pathologies a result of trauma. Left pedal phalanx I-1 and left dorsal rib 10 are both fractured with extensive callus formation in the later stages of healing. Left dorsal rib 7 (L7) and right dorsal rib 10 (R10) exhibit impacted fractures compressed 26 mm and 24 mm, respectively. The fracture morphologies in L7 and R10 indicate this animal suffered a strong compressive force coincident with the long axis of the ribs. All three rib pathologies and the pathological left phalanx I-1 are consistent with injuries sustained in a fall. However, it is clear from the healing exhibited by these fractures that this individual survived the fall. In addition to traumatic fractures, left dorsal rib 10 and possibly left phalanx I-1 have a morphology consistent with post-traumatic infection in the form of osteomyelitis. The CT scans of left metacarpal IV revealed the presence of an abscess within the medullary cavity consistent with a subacute form of hematogenous osteomyelitis termed a Brodie abscess. This is only the second reported Brodie abscess in non-avian dinosaurs and the first documented occurrence in herbivorous dinosaurs. The presence of a Brodie abscess, known only in mammalian pathological literature, suggest mammalian descriptors for bone infection may be applicable to non-avian dinosaurs.

Deer antler stem cells are a novel type of cells that sustain full regeneration of a mammalian organ\u2014deer antler

Deer antlers are extraordinary mammalian organs that can fully regenerate annually. Antler renewal is a stem cell-based epimorphic process and antler stem (AS) cells can initiate de novo generation of antlers in postnatal mammals. However, although being called stem cells, the AS cells have not been characterized at molecular level based on the stem cell criteria. Comprehensive characterization of the AS cells would undoubtedly help to decipher the mechanism underlying the full regeneration of deer antlers, the only case of stem cell-based epimorphic regeneration in mammals. In the present study, three types of AS cells (antlerogenic periosteal cells APCs, for initial pedicle and first antler formation; pedicle periosteal cells PPC, for annual antler regeneration; and reserve mesenchyme cells RMCs, for rapid antler growth), were isolated for comprehensive molecular characterization. A horn-growth-related gene, RXFP2, was found to be expressed only in AS cells lineages but not in the facial periosteal cells (FPCs, locates geographically in the vicinity of the APCs or PPCs), suggesting the RXFP2 might be a specific marker for the AS cell lineage in deer. Our results demonstrated that AS cells expressed classic MSC markers including surface markers CD73, CD90, CD105 and Stro-1. They also expressed some of the markers including Tert, Nestin, S100A4, nucleostemin and C-Myc, suggesting that they have some attributes of the ESCs. Microinjection of male APC into deer blastocysts resulted in one female foetus (110 days gestation) recovered with obvious pedicle primordia with both male and female genotype detected in the ovary. In conclusion, the AS cells should be defined as MSCs but with partial attributes of ESCs.

Use of cast antlers to assess antler size variation in red deer populations: effects of mast seeding, climate and population features in Mediterranean environments

AbstractFundamental understanding of the factors influencing cervid antler size, development and investment has been traditionally drawn from harvest data. However, depending on the hunting tactic, harvest data may not represent a random sample of the population leading to possible inferential biases. Cast antlers may represent an alternative, cost‐effective and non‐invasive method. We used 4756 red deer (Cervus elaphus L.) cast antlers collected during a 10‐year period to evaluate the relationship between annual antler gross score and three key environmental components that determine habitat quality and resource availability in Mediterranean systems: (1) population traits (density and male age structure), (2) acorn yield and (3) a proxy of plant productivity [Real Bioclimatic Index(RBI)]. Population traits and acorn yield were measured before antler formation (autumn/winter) whereas RBI was calculated before (autumn/winter) and during (spring) antler formation. Population traits explained the highest amount of variance in antler score, followed by acorn yield and spring RBI, while no effect was found for autumn/winter RBI. Antler gross score was negatively related to population density but positively associated with acorn yield, spring RBI and male age structure. Interestingly, a significant interaction between population traits and acorn yield suggests a disproportional effect of population traits on antler size during non‐mast years (poor acorn crops), whereas no significant population effect was observed during mast years. Similarly, we found a positive effect of spring RBI on antlers when density was medium or low and/or age structure was balanced or older. These findings have important ecological implications in environments with high inter‐annual resources variability where high population densities lead to strong intraspecific competition during years of low food availability (e.g. during non‐mast years or drier springs), producing large antler size variation. Finally, although cast antlers reflect changes in environmental conditions we do not recommend their use unless reliable data on age structure is available.

Mineral part of deer antler as production basis for biologically active substances

An analysis of the structure and chemical composition of the deer antlers of the Altai is carried out. It is shown that the mineral substance of soft antlers is structurally x-ray amorphous with gradual crystallization of hydroxyapatite as antlers become ossified with age or when the analyzed region approaches the frontal bone. The internal structure of the antler is represented by a highly porous material with an average pore diameter of about 100 μ m in the presence of pores with a diameter less than 10 nm. According to the chemical composition, the mineral part of the young 2-3 terminal antlers as compared to the ordinary bone is substantially impoverished with calcium and phosphorus, but is enriched with such impurities as silicon, aluminum, and alkaline elements. This hampers the crystallization of hydroxyapatite and forms distinct structures. On the basis of the data obtained, a model for the formation of antlers is proposed, which includes the formation at the early stages in the mineral part of zeolite-like x-ray amorphous structures that ensure the catalytic synthesis and accumulation of biologically active substances, in particular, lipids. With the aging of the antlers and the subsequent addition of calcium, a hydroxyapatite mineral corresponding to the composition of the ordinary bone is formed.

Custom-built tools for the study of deer antler biology.

Deer antlers can be developed into multiple novel models to study growth and development of tissues for biomedical research. To facilitate this process, we have invented and further refined five custom-built tools through three decades of antler research. These are: 1. Pedicle growth detector to pinpoint the timing when pedicle growth is initiated, thus stimuli for pedicle and first antler formation can be investigated and identified. 2. Thin periosteum slice cutter to thinly slice (0.2mm or 0.7 mm thick) a whole piece of antlerogenic periosteum (AP) or pedicle periosteum (PP), which facilitates gene delivery into cells resident in these tissues, thus making transgenic antlers possible. 3. The porous periosteum multi-needle punch to effectively loosen the dense AP or PP tissue. This allows most cells of the periosteum to come into direct contact with treating solutions, thus making artificial manipulation of antler development possible. 4. The intra-dermal pocket maker to cut the thin dermal tissue (less than 2 mm in thickness) of a male deer calf horizontally into two layers to make an intra-dermal pocket. This allows loading of AP tissue intra-dermally to test the theory of "antler stem cell niche" in vivo. 5. The sterile periosteum sampling system to allow aseptic collection of the AP, PP or the antler growth centre tissue on farm, thus allowing antler generation, regeneration or rapid growth to be investigated in vitro. Overall, we believe the application of contemporary cellular and molecular biological techniques coupled with these custom-built tools would greatly promote the establishment of this unique and novel model for the benefits of biomedical research, and hence human health.

Knappable silcrete in the Cretaceous Antlers Formation of Oklahoma and Texas

Although occasionally manifest in archaeological collections, silcrete is an understudied raw material on the Southern Plains of North America. Over the past decade, however, archaeologists have discovered prehistorically exploited silcretes in strata along the Southern High Plains (Llano Estacado) margins and in lag deposits far east of that region. These latter occur at scattered locations where Holocene erosion has exposed them associated with early Cretaceous near-shore sands geologically identified as the Antlers Formation of the Trinity Group. Two such exposures are reported for southern Oklahoma. Both appear to be lag deposits of lenses or seams that were sporadically exploited by people between 13,000 and 800years ago. This gray to white, fine-grained stone is petrographically and chemically different from well-rounded quartzite gravels also found in the Antlers Formation. The reported silcrete clasts commonly occur at the boundary between the Antlers Formation and the overlying soil, and the material's genesis is probably the result of silica-rich groundwater seeping into the quartz-laden Antlers sand. Archaeological finds attest to Antlers silcrete primarily being knapped by early Holocene hunter-gatherers who sought and used it mainly for spear points. Silcrete artifact distributions tend to be near the sources of this material. With more surveys, additional source locations are expected to be found. Hopefully, these will enhance understanding the material's genesis as well as its use by Southern Plains natives.

Taxonomic revision of tribosphenic mammals from the Lower Cretaceous Antlers Formation of Texas and Oklahoma, USA

There are five taxa of tribosphenic mammals in the Early Cretaceous Antlers Formation of Texas and Oklahoma, USA: a basal stem therian (Kermackia texana), stem therians near the eutherian-metatherian dichotomy (Holoclemensia texana and Pappotherium pattersoni), and stem marsupials (Atokatheridium boreni and Oklatheridium szalayi). K. texana has a primitive therian postcanine formula with three molars, replacement of p5, M3 with low protocone and no conules, lower molars with a large trigonid angle, oblique protocristid, paraconid smaller than metaconid (except m3), strong distal metacristid, narrow talonid, small talonid basin, and small entoconid (absent on m3). H. texana also has replacement in the fifth premolar locus and three molars. It is more derived in having a larger protoconal region with higher protocone and conules present, lack of distal metacristid, smaller trigonid angle, transverse protocristid, and wide talonid with larger talonid basin. It is similar to Eutheria by having M1 with reduced ectoflexus, semimolariform p5, and low trigonid angle with transverse protocristid. Holoclemensia cannot be referred to Eutheria because of the lack of the second rank postvallum/prevallid shear and unwinged conules. P. pattersoni (=Slaughteria eruptens) has replacement in the fifth premolar position, premolariform p5, and three molars (symplesiomorphies for Theria). It is more derived than Holoclemensia in having a wider and shorter talonid. Pappotherium is similar to Eutheria in having a low trigonid angle, transverse protocristid, and the cristid obliqua labial to the protocristid notch. It cannot be attributed to the Eutheria because of the narrow protoconal region, low protocone, small conules lacking internal cristae, postprotocrista not extending labially past the metacone base, and a small talonid basin. Atokatheridium boreni and Oklatheridium szalayi (=O. minax, syn. nov.) have four molars and emphasis on the postvallum/prevallid shear (large metacone on M2, strong postmetacrista, paraconid higher than metaconid). These taxa cannot be attributed to the Deltatheroida because of large protoconal region with winged conules. Oklatheridium is further different from the Deltatheroida in having a wider talonid and better developed entoconid.

Deer antler: a unique model for studying mammalian organ morphogenesis

It is now widely accepted that organ morphogenesis in the lower animals, such as amphibians, is encoded by bioelectricity. Whether this finding applies to mammals is not known, a situation which is at least partially caused by the lack of suitable models. Deer antlers are complex mammalian organs, and their morphogenetic information resides in a primordium, the periosteum overlying the frontal crest of a prepubertal deer. The present paper reviews (1) the influence of morphogenetic information on antler formation and regeneration, and proposes that antlers are an appropriate organ for studying mammalian organ morphogenesis and (2) the storage, duplication and transferring pathways of morphogenetic information for deer antlers, and outlines a preliminary idea about how to understand the morphogenesis of mammalian organs through an involvement of bioelectricity. We believe that findings made using the deer antler model will benefit human health and wellbeing.

The skeletal morphology of the solemydid turtle Naomichelys speciosa from the Early Cretaceous of Texas

The fossil record of solemydid turtles is primarily based on isolated fragments collected from Late Jurassic to Late Cretaceous sediments throughout North America and Europe and little is therefore known about the morphology and evolutionary history of the group. We here provide a detailed description of the only known near-complete solemydid skeleton, which was collected from the Lower Cretaceous (Aptian–Albian) Antlers Formation of Texas during the mid-twentieth century, but essentially remains undescribed to date. Though comparison is limited, the skeleton is referred to Naomichelys speciosa, which is based on an isolated entoplastron from the Lower Cretaceous (Aptian–Albian) Kootenai (Cloverly) Formation of Montana. The absence of temporal emarginations, contribution of the jugals to the orbits, and a clear subdivision of the middle and inner cavities, and the presence of elongate postorbitals, posteriorly expanded squamosals, a triangular fossa at the posterior margin of the squamosals, an additional pair of tubercula basioccipitale that is formed by the pterygoids, foramina pro ramo nervi vidiani (VII) that are visible in ventral view, shell sculpturing consisting of high tubercles, a large entoplastron with entoplastral scute, V-shaped anterior peripherals, and limb osteoderms with tubercular sculpture diagnose Naomichelys speciosa as a representative of Solemydidae. The full visibility of the parabasisphenoid complex in ventral view, the presence of an expanded symphyseal shelf, and the unusual ventromedial folding of the coronoid process are the primary characteristics that distinguish Naomichelys speciosa from the near-coeval European taxon Helochelydra nopcsai.

Revision of the sauropod dinosaurs of the Lower Cretaceous Trinity Group, southern USA, with the description of a new genus

Early Cretaceous sauropods were among the first dinosaurs discovered in North America, but several aspects of their taxonomy and evolution remain poorly understood. Much of this ambiguity stems from lack of anatomical overlap among taxa and the 125-year-long taxonomic confusion surrounding the sauropods Astrodon and Pleurocoelus. New discoveries have begun to remedy the first problem, but a lack of autapomorphies in their holotypes and skeletal associations among their hypodigms renders Astrodon johnstoni, Pleurocoelus altus and Pleurocoelus nanus nomina dubia. Herein I examine the affinities of sauropods from the Trinity Group of Texas and Oklahoma previously referred to as ‘Pleurocoelus’ or ‘Astrodon’. Some of this material currently comprises the genera Paluxysaurus and Sauroposeidon from laterally equivalent strata in Texas and Oklahoma, respectively. Although representative individuals of Paluxysaurus are only two-thirds the size of Sauroposeidon, bone histology of Paluxysaurus indicates that the individuals from the type locality were not near adult size. The similar provenance, lack of morphological differences, and shared unique features support referral of Paluxysaurus to Sauroposeidon. Other sauropod remains from the Trinity Group are not referable to ‘Pleurocoelus’, ‘Astrodon’ or Sauroposeidon. Some of these remains comprise the holotype of Astrophocaudia slaughteri gen. et sp. nov., a basal titanosauriform diagnosed by a hyposphene–hypantrum system in the caudal vertebrae. A sauropod hind limb previously referred to ‘Pleurocoelus’ is instead referable to Cedarosaurus weiskopfae based on shared features of the pes. Cladistic analysis indicates that Astrophocaudia and Sauroposeidon are members of Somphospondyli, whereas Cedarosaurus is a brachiosaurid. The Trinity Group of Texas and laterally equivalent Antlers Formation of Oklahoma exhibit similar dinosaur faunas at the generic and specific levels to the Cloverly Formation of Wyoming. This homogeneity with respect to latitude stands in marked contrast to the latitudinal variation in dinosaur communities that developed later in the Cretaceous. http://zoobank.org/urn:lsid:zoobank.org:pub:FE82D372-7ADA-4870-9572-3A3F607D39CE

Labeling studies on cortical bone formation in the antlers of red deer (Cervus elaphus)

The formation and mineralization process of antlers, which constitute the fastest growing bones in vertebrates, is still not fully understood. We used oxytetracycline injections to label different stages of bone formation in antlers of 14 red deer between days 28 and 156 of antler growth. Results show that initially a trabecular scaffold of woven bone is formed which largely replaces a pre-existing scaffold of mineralized cartilage. Lamellar bone is then deposited and from about day 70 onwards, primary osteons fill in the longitudinal tubes lined by the scaffold in a proximal to distal sequence. Mineral apposition rate (MAR) in early stages of primary osteon formation is very high (average 2.15μm/d). Lower MARs were recorded for later stages of primary osteon formation (1.56μm/d) and for the smaller secondary osteons (0.89μm/d). Results suggest a peak in mineral demand around day 100 when the extent of mineralizing surfaces is maximal. A few secondary osteons were formed in a process of antler modeling rather than remodeling, as it occurred simultaneously with formation of primary osteons. The degree of cortical porosity reflects a reduction in MAR during later stages of osteonal growth, whereas cortical thickness is determined earlier. Injections given when the antlers were largely or completely clean from velvet produced no labels in antler bone, strongly suggesting that antlers are dead after velvet shedding. The rapidity of antler mineralization and the short lifespan of antlers make them an extraordinary model to assess the effects of chemicals impairing or promoting bone mineralization.

Morphogenetic aspects of deer antler development

Deer antlers are unique mammalian appendages that have potential for application as a valuable model for biomedical research, such as organ regeneration, bone development and growth control. In this review we described the morphogenetic aspects of antler development, by summarizing relevant information accumulated over the course of our antler research in combine with other published papers. Antler development consists of two distinct phenomena: generation and regeneration. Generation starts with the initiation of a pair of pedicles, permanent bony protuberances on the skull of a male deer, when the animal approaches puberty; proceeds to transformation to antlers when the pedicles reach a species-specific height (around 5 cm in red deer); and terminates with total antler calcification and velvet (antler skin) shedding. Regeneration commences in the spring of the subsequent year with the initiation of new soft antlers growing from the pedicle stumps that remain following the casting of the previous hard antlers; proceeds to the elaboration of multi-branched antlers in summer; and ends up with total antler calcification and velvet shedding in autumn, resulting in the formation of hard bony antlers in winter. Therefore, this paper not only lays the foundation for further development of this valuable biomedical model, but also provides comprehensive background knowledge that will be of use to readers when reading the papers featured in this special issue.

New information on the cranial anatomy of Acrocanthosaurus atokensis and its implications for the phylogeny of Allosauroidea (Dinosauria: Theropoda).

BackgroundAllosauroidea has a contentious taxonomic and systematic history. Within this group of theropod dinosaurs, considerable debate has surrounded the phylogenetic position of the large-bodied allosauroid Acrocanthosaurus atokensis from the Lower Cretaceous Antlers Formation of North America. Several prior analyses recover Acrocanthosaurus atokensis as sister taxon to the smaller-bodied Allosaurus fragilis known from North America and Europe, and others nest Acrocanthosaurus atokensis within Carcharodontosauridae, a large-bodied group of allosauroids that attained a cosmopolitan distribution during the Early Cretaceous.Methodology/Principal FindingsRe-evaluation of a well-preserved skull of Acrocanthosaurus atokensis (NCSM 14345) provides new information regarding the palatal complex and inner surfaces of the skull and mandible. Previously inaccessible internal views and articular surfaces of nearly every element of the skull are described. Twenty-four new morphological characters are identified as variable in Allosauroidea, combined with 153 previously published characters, and evaluated for eighteen terminal taxa. Systematic analysis of this dataset recovers a single most parsimonious topology placing Acrocanthosaurus atokensis as a member of Allosauroidea, in agreement with several recent analyses that nest the taxon well within Carcharodontosauridae.Conclusions/SignificanceA revised diagnosis of Acrocanthosaurus atokensis finds that the species is distinguished by four primary characters, including: presence of a knob on the lateral surangular shelf; enlarged posterior surangular foramen; supraoccipital protruding as a double-boss posterior to the nuchal crest; and pneumatic recess within the medial surface of the quadrate. Furthermore, the recovered phylogeny more closely agrees with the stratigraphic record than hypotheses that place Acrocanthosaurus atokensis as more closely related to Allosaurus fragilis. Fitch optimization of body size is also more consistent with the placement of Acrocanthosaurus atokensis within a clade of larger carcharodontosaurid taxa than with smaller-bodied taxa near the base of Allosauroidea. This placement of Acrocanthosaurus atokensis supports previous hypotheses of a global carcharodontosaurid radiation during the Early Cretaceous.