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1.
Proc Natl Acad Sci U S A ; 121(24): e2316419121, 2024 Jun 11.
Article in English | MEDLINE | ID: mdl-38830089

ABSTRACT

The extinction of the woolly rhinoceros (Coelodonta antiquitatis) at the onset of the Holocene remains an enigma, with conflicting evidence regarding its cause and spatiotemporal dynamics. This partly reflects challenges in determining demographic responses of late Quaternary megafauna to climatic and anthropogenic causal drivers with available genetic and paleontological techniques. Here, we show that elucidating mechanisms of ancient extinctions can benefit from a detailed understanding of fine-scale metapopulation dynamics, operating over many millennia. Using an abundant fossil record, ancient DNA, and high-resolution simulation models, we untangle the ecological mechanisms and causal drivers that are likely to have been integral in the decline and later extinction of the woolly rhinoceros. Our 52,000-y reconstruction of distribution-wide metapopulation dynamics supports a pathway to extinction that began long before the Holocene, when the combination of cooling temperatures and low but sustained hunting by humans trapped woolly rhinoceroses in suboptimal habitats along the southern edge of their range. Modeling indicates that this ecological trap intensified after the end of the last ice age, preventing colonization of newly formed suitable habitats, weakening stabilizing metapopulation processes, triggering the extinction of the woolly rhinoceros in the early Holocene. Our findings suggest that fragmentation and resultant metapopulation dynamics should be explicitly considered in explanations of late Quaternary megafauna extinctions, sending a clarion call to the fragility of the remaining large-bodied grazers restricted to disjunct fragments of poor-quality habitat due to anthropogenic environmental change.


Subject(s)
Extinction, Biological , Fossils , Perissodactyla , Population Dynamics , Animals , Ecosystem , DNA, Ancient/analysis , Paleontology
2.
PeerJ ; 12: e17436, 2024.
Article in English | MEDLINE | ID: mdl-38832040

ABSTRACT

Postmortem body curvature introduces error in fish morphometric data. Compared to living fish, the causes of such body curvature in fossils may be due to additive taphonomic processes that have been widely studied. However, a protocol that helps to correct its effect upon morphometric data remains unexplored. Here, we test two different mathematical approaches (multivariate regression and the so-called 'unbending functions') available to tackle fish geometric morphometric data in two exceptionally preserved gonorynchiformes fossil fishes, Rubiesichthys gregalis and Gordichthys conquensis, from the Las Hoyas deposits (Early Cretaceous, Spain). Although both methods successfully correct body curvature (i.e., removing misleading geometric variation), our results show that traditional approaches applied in living fishes might not be appropriate to fossil ones, because of the additional anatomical alterations. Namely, the best result for 2D fossil fishes is achieved by correcting the arching of the specimens (mathematically "unbending" them). Ultimately, the effect of body curvature on morphometric data is largely taxon independent and morphological diversity mitigates its effect, but size is an important factor to take into account (because larger individuals tend to be less curved).


Subject(s)
Fishes , Fossils , Animals , Fishes/anatomy & histology , Spain
3.
Geobiology ; 22(3): e12598, 2024.
Article in English | MEDLINE | ID: mdl-38700417

ABSTRACT

Tonian (ca. 1000-720 Ma) marine environments are hypothesised to have experienced major redox changes coinciding with the evolution and diversification of multicellular eukaryotes. In particular, the earliest Tonian stratigraphic record features the colonisation of benthic habitats by multicellular macroscopic algae, which would have been powerful ecosystem engineers that contributed to the oxygenation of the oceans and the reorganisation of biogeochemical cycles. However, the paleoredox context of this expansion of macroalgal habitats in Tonian nearshore marine environments remains uncertain due to limited well-preserved fossils and stratigraphy. As such, the interdependent relationship between early complex life and ocean redox state is unclear. An assemblage of macrofossils including the chlorophyte macroalga Archaeochaeta guncho was recently discovered in the lower Mackenzie Mountains Supergroup in Yukon (Canada), which archives marine sedimentation from ca. 950-775 Ma, permitting investigation into environmental evolution coincident with eukaryotic ecosystem evolution and expansion. Here we present multi-proxy geochemical data from the lower Mackenzie Mountains Supergroup to constrain the paleoredox environment within which these large benthic macroalgae thrived. Two transects show evidence for basin-wide anoxic (ferruginous) oceanic conditions (i.e., high FeHR/FeT, low Fepy/FeHR), with muted redox-sensitive trace metal enrichments and possible seasonal variability. However, the weathering of sulfide minerals in the studied samples may obscure geochemical signatures of euxinic conditions. These results suggest that macroalgae colonized shallow environments in an ocean that remained dominantly anoxic with limited evidence for oxygenation until ca. 850 Ma. Collectively, these geochemical results provide novel insights into the environmental conditions surrounding the evolution and expansion of benthic macroalgae and the eventual dominance of oxygenated oceanic conditions required for the later emergence of animals.


Subject(s)
Biological Evolution , Fossils , Oxidation-Reduction , Geologic Sediments/chemistry , Geologic Sediments/analysis , Eukaryota , Canada , Ecosystem , Chlorophyta
4.
Geobiology ; 22(3): e12597, 2024.
Article in English | MEDLINE | ID: mdl-38700422

ABSTRACT

Ediacara-type macrofossils appear as early as ~575 Ma in deep-water facies of the Drook Formation of the Avalon Peninsula, Newfoundland, and the Nadaleen Formation of Yukon and Northwest Territories, Canada. Our ability to assess whether a deep-water origination of the Ediacara biota is a genuine reflection of evolutionary succession, an artifact of an incomplete stratigraphic record, or a bathymetrically controlled biotope is limited by a lack of geochronological constraints and detailed shelf-to-slope transects of Ediacaran continental margins. The Ediacaran Rackla Group of the Wernecke Mountains, NW Canada, represents an ideal shelf-to-slope depositional system to understand the spatiotemporal and environmental context of Ediacara-type organisms' stratigraphic occurrence. New sedimentological and paleontological data presented herein from the Wernecke Mountains establish a stratigraphic framework relating shelfal strata in the Goz/Corn Creek area to lower slope deposits in the Nadaleen River area. We report new discoveries of numerous Aspidella hold-fast discs, indicative of frondose Ediacara organisms, from deep-water slope deposits of the Nadaleen Formation stratigraphically below the Shuram carbon isotope excursion (CIE) in the Nadaleen River area. Such fossils are notably absent in coeval shallow-water strata in the Goz/Corn Creek region despite appropriate facies for potential preservation. The presence of pre-Shuram CIE Ediacara-type fossils occurring only in deep-water facies within a basin that has equivalent well-preserved shallow-water facies provides the first stratigraphic paleobiological support for a deep-water origination of the Ediacara biota. In contrast, new occurrences of Ediacara-type fossils (including juvenile fronds, Beltanelliformis, Aspidella, annulated tubes, and multiple ichnotaxa) are found above the Shuram CIE in both deep- and shallow-water deposits of the Blueflower Formation. Given existing age constraints on the Shuram CIE, it appears that Ediacaran organisms may have originated in the deeper ocean and lived there for up to ~15 million years before migrating into shelfal environments in the terminal Ediacaran. This indicates unique ecophysiological constraints likely shaped the initial habitat preference and later environmental expansion of the Ediacara biota.


Subject(s)
Biota , Fossils , Geologic Sediments , Geologic Sediments/chemistry , Geologic Sediments/analysis , Carbon Isotopes/analysis , Yukon Territory , Newfoundland and Labrador , Paleontology , Northwest Territories
5.
Nat Commun ; 15(1): 3703, 2024 May 02.
Article in English | MEDLINE | ID: mdl-38697988

ABSTRACT

Phosphorus plays a crucial role in controlling biological productivity, but geological estimates of phosphate concentrations in the Precambrian ocean, during life's origin and early evolution, vary over several orders of magnitude. While reduced phosphorus species may have served as alternative substrates to phosphate, their bioavailability on the early Earth remains unknown. Here, we reconstruct the phylogenomic record of life on Earth and find that phosphate transporting genes (pnas) evolved in the Paleoarchean (ca. 3.6-3.2 Ga) and are consistent with phosphate concentrations above modern levels ( > 3 µM). The first gene optimized for low phosphate levels (pstS; <1 µM) appeared around the same time or in the Mesoarchean depending on the reconstruction method. Most enzymatic pathways for metabolising reduced phosphorus emerged and expanded across the tree of life later. This includes phosphonate-catabolising CP-lyases, phosphite-oxidising pathways and hypophosphite-oxidising pathways. CP-lyases are particularly abundant in dissolved phosphate concentrations below 0.1 µM. Our results thus indicate at least local regions of declining phosphate levels through the Archean, possibly linked to phosphate-scavenging Fe(III), which may have limited productivity. However, reduced phosphorus species did not become widely used until after the Paleoproterozoic Great Oxidation Event (2.3 Ga), possibly linked to expansion of the biosphere at that time.


Subject(s)
Phosphates , Phosphorus , Phylogeny , Phosphorus/metabolism , Phosphates/metabolism , Evolution, Molecular , Earth, Planet , Fossils
6.
PLoS One ; 19(5): e0303198, 2024.
Article in English | MEDLINE | ID: mdl-38701057

ABSTRACT

The study of morphological characteristics and growth information in fish scales is a crucial component of modern fishery biological research, while it has been less studied in fossil materials. This paper presents a detailed morphological description and growth analysis of a fossil ctenoid scale obtained from the Upper Cretaceous Campanian lacustrine deposits in northeastern China. The morphological features of this fossil scale are well-preserved and consistent with the structures found in ctenoid scales of extant fish species and display prominent ring ornamentation radiating outward from the central focus, with grooves intersecting the rings. A comparative analysis of the morphological characteristics between the fossil ctenoid scale and those well-studied extant fish Mugilidae allows us to explore the applicability of modern fishery biological research methods to the field of fossil scales. The scale length, scale width, the vertical distance from the focus to the apex of the scale, and the total number of radii have been measured. The age of the fish that possessed this ctenoid scale has been estimated by carefully counting the annuli, suggesting an age equal to or more than seven years. The distribution of growth rings on the scale potentially reflects the warm paleoclimatic condition and fish-friendly paleoenvironment prevalent during that period. This paper, moreover, serves as a notable application of fishery biological methods in the examination of fossil materials.


Subject(s)
Fossils , China , Animals , Fishes/anatomy & histology , Fishes/growth & development , Animal Scales/anatomy & histology
7.
Geobiology ; 22(3): e12601, 2024.
Article in English | MEDLINE | ID: mdl-38725142

ABSTRACT

While stromatolites, and to a lesser extent thrombolites, have been extensively studied in order to unravel Precambrian (>539 Ma) biological evolution, studies of clastic-dominated microbially induced sedimentary structures (MISS) are relatively scarce. The lack of a consolidated record of clastic microbialites creates questions about how much (and what) information on depositional and taphonomic settings can be gleaned from these fossils. We used µCT scanning, a non-destructive X-ray-based 3D imaging method, to reconstruct morphologies of ancient MISS and mat textures in two previously described coastal Archaean samples from the ~3.48 Ga Dresser Formation, Pilbara, Western Australia. The aim of this study was to test the ability of µCT scanning to visualize and make 3D measurements that can be used to interpret the biotic-environmental interactions. Fossil MISS including mat laminae with carpet-like textures in one sample and mat rip-up chips in the second sample were investigated. Compiled δ13C and δ34S analyses of specimens from the Dresser Fm. are consistent with a taxonomically diverse community that could be capable of forming such MISS. 3D measurements of fossil microbial mat chips indicate significant biostabilization and suggest formation in flow velocities >25 cm s-1. Given the stratigraphic location of these chips in a low-flow lagoonal layer, we conclude that these chips formed due to tidal influence, as these assumed velocities are consistent with recent modeling of Archaean tides. The success of µCT scanning in documenting these microbialite features validates this technique both as a first step analysis for rare samples prior to the use of more destructive techniques and as a valuable tool for gaining insight into microbialite taphonomy.


Subject(s)
Fossils , Geologic Sediments , Imaging, Three-Dimensional , X-Ray Microtomography , Geologic Sediments/microbiology , Western Australia , Archaea
9.
Nat Commun ; 15(1): 3808, 2024 May 07.
Article in English | MEDLINE | ID: mdl-38714651

ABSTRACT

Euchelicerata is a clade of arthropods comprising horseshoe crabs, scorpions, spiders, mites and ticks, as well as the extinct eurypterids (sea scorpions) and chasmataspidids. The understanding of the ground plans and relationships between these crown-group euchelicerates has benefited from the discovery of numerous fossils. However, little is known regarding the origin and early evolution of the euchelicerate body plan because the relationships between their Cambrian sister taxa and synziphosurines, a group of Silurian to Carboniferous stem euchelicerates with chelicerae and an unfused opisthosoma, remain poorly understood owing to the scarce fossil record of appendages. Here we describe a synziphosurine from the Lower Ordovician (ca. 478 Ma) Fezouata Shale of Morocco. This species possesses five biramous appendages with stenopodous exopods bearing setae in the prosoma and a fully expressed first tergite in the opisthosoma illuminating the ancestral anatomy of the group. Phylogenetic analyses recover this fossil as a member of the stem euchelicerate family Offacolidae, which is characterized by biramous prosomal appendages. Moreover, it also shares anatomical features with the Cambrian euarthropod Habelia optata, filling the anatomical gap between euchelicerates and Cambrian stem taxa, while also contributing to our understanding of the evolution of euchelicerate uniramous prosomal appendages and tagmosis.


Subject(s)
Arthropods , Biological Evolution , Fossils , Phylogeny , Animals , Arthropods/anatomy & histology , Arthropods/classification , Arthropods/genetics , Morocco , Horseshoe Crabs/anatomy & histology , Horseshoe Crabs/genetics , Horseshoe Crabs/classification , Biodiversity
10.
J Morphol ; 285(5): e21700, 2024 May.
Article in English | MEDLINE | ID: mdl-38717130

ABSTRACT

A sample of phosphatized, originally calcareous, mollusk shells from the Katian age uppermost Mójcza Limestone at its type locality yielded a few hundred polyplacophoran plates. The chelodids are very rare among them. Three septemchitonid species dominate. They represent a gradation from underived steep roof-like plates to almost cylindrical ones, leaving only a narrow ventral slit for the foot. Apparently, this represents the first step toward the extremely derived 'segmented clam' Bauplan of the Silurian Carnicoleus, with plates completely closed at the venter except for the mouth and anal openings. To enable growth, the plates became thinner and more flexible (or perhaps resorbed) along the dorsum. The tendency toward reduction of the ventral gap of the plates in the early Paleozoic septemchitonid polyplacophorans implies their lack of ability to cling to the substrate with a muscular foot. In compensation, their plates changed toward a more efficient protective function, covering the animal body sides more and more completely. This may explain the origin of the ventral furrow of extant solenogasters hiding the rudimentary foot. An opposite route was chosen by the coeval Acaenoplax lineage, in which the plates did not contact each other, exposing much of the soft body on the dorsum. In both cases the animals appeared to be worm-like, perhaps representing different ways of evolution from the Paleozoic chitons to the extant aplacophorans.


Subject(s)
Fossils , Animals , Fossils/anatomy & histology , Polyplacophora/anatomy & histology , Biological Evolution , Animal Shells/anatomy & histology
11.
PLoS One ; 19(5): e0302646, 2024.
Article in English | MEDLINE | ID: mdl-38709766

ABSTRACT

The analysis of the DNA entrapped in ancient shells of molluscs has the potential to shed light on the evolution and ecology of this very diverse phylum. Ancient genomics could help reconstruct the responses of molluscs to past climate change, pollution, and human subsistence practices at unprecedented temporal resolutions. Applications are however still in their infancy, partly due to our limited knowledge of DNA preservation in calcium carbonate shells and the need for optimized methods for responsible genomic data generation. To improve ancient shell genomic analyses, we applied high-throughput DNA sequencing to 27 Mytilus mussel shells dated to ~111-6500 years Before Present, and investigated the impact, on DNA recovery, of shell imaging, DNA extraction protocols and shell sub-sampling strategies. First, we detected no quantitative or qualitative deleterious effect of micro-computed tomography for recording shell 3D morphological information prior to sub-sampling. Then, we showed that double-digestion and bleach treatment of shell powder prior to silica-based DNA extraction improves shell DNA recovery, also suggesting that DNA is protected in preservation niches within ancient shells. Finally, all layers that compose Mytilus shells, i.e., the nacreous (aragonite) and prismatic (calcite) carbonate layers, with or without the outer organic layer (periostracum) proved to be valuable DNA reservoirs, with aragonite appearing as the best substrate for genomic analyses. Our work contributes to the understanding of long-term molecular preservation in biominerals and we anticipate that resulting recommendations will be helpful for future efficient and responsible genomic analyses of ancient mollusc shells.


Subject(s)
Animal Shells , Genomics , Mollusca , Animals , Genomics/methods , Mollusca/genetics , X-Ray Microtomography , Calcium Carbonate , High-Throughput Nucleotide Sequencing , Fossils
12.
PLoS One ; 19(5): e0302889, 2024.
Article in English | MEDLINE | ID: mdl-38709805

ABSTRACT

Semi-articulated remains of a large chelonioid turtle from the Turonian strata (Upper Cretaceous; ca. 93.9-89.8 Myr) near Sant'Anna d'Alfaedo (Verona province, northeastern Italy) are described for the first time. Together with the skeletal elements, the specimen also preserves pebbles inside the thoracic area which are lithologically distinct from the surrounding matrix. These allochthonous clasts are here interpreted as geo-gastroliths, in-life ingested stones that resided in the digestive tract of the animal. This interpretation marks the first reported evidence of geophagy in a fossil marine turtle. SEM-EDS analysis, together with macroscopic petrological characterization, confirm the presence of both siliceous and carbonatic pebbles. These putative geo-gastroliths have morphometries and size ranges more similar to those of gastroliths in different taxa (fossils and extant) than allochthonous "dropstone" clasts from the same deposit that were carried by floating vegetation A dense pitted pattern of superficial erosion is microscopically recognizable on the carbonatic gastroliths, consistent with surface etching due to gastric acids. The occurrence of a similar pattern was demonstrated by the experimental etching of carbonatic pebbles with synthetic gastric juice. Gut contents of modern green sea turtles (Chelonia mydas) were surveyed for substrate ingestion, providing direct evidence of geophagic behavior in extant chelonioids. Comparison with modern turtle dietary habits may suggests that the pebbles were ingested as a way to supplement calcium after or in preparation for egg deposition, implying that the studied specimen was possibly a gravid female.


Subject(s)
Fossils , Turtles , Animals , Turtles/anatomy & histology , Italy , Paleontology
13.
PeerJ ; 12: e17277, 2024.
Article in English | MEDLINE | ID: mdl-38708352

ABSTRACT

Background: Squamata (lizards, snakes, and amphisbaenians) is a Triassic lineage with an extensive and complex biogeographic history, yet no large-scale study has reconstructed the ancestral range of early squamate lineages. The fossil record indicates a broadly Pangaean distribution by the end- Cretaceous, though many lineages (e.g., Paramacellodidae, Mosasauria, Polyglyphanodontia) subsequently went extinct. Thus, the origin and occupancy of extant radiations is unclear and may have been localized within Pangaea to specific plates, with potential regionalization to distinct Laurasian and Gondwanan landmasses during the Mesozoic in some groups. Methods: We used recent tectonic models to code extant and fossil squamate distributions occurring on nine discrete plates for 9,755 species, with Jurassic and Cretaceous fossil constraints from three extinct lineages. We modeled ancestral ranges for crown Squamata from an extant-only molecular phylogeny using a suite of biogeographic models accommodating different evolutionary processes and fossil-based node constraints from known Jurassic and Cretaceous localities. We hypothesized that the best-fit models would not support a full Pangaean distribution (i.e., including all areas) for the origin of crown Squamata, but would instead show regionalization to specific areas within the fragmenting supercontinent, likely in the Northern Hemisphere where most early squamate fossils have been found. Results: Incorporating fossil data reconstructs a localized origin within Pangaea, with early regionalization of extant lineages to Eurasia and Laurasia, while Gondwanan regionalization did not occur until the middle Cretaceous for Alethinophidia, Scolecophidia, and some crown Gekkotan lineages. While the Mesozoic history of extant squamate biogeography can be summarized as a Eurasian origin with dispersal out of Laurasia into Gondwana, their Cenozoic history is complex with multiple events (including secondary and tertiary recolonizations) in several directions. As noted by previous authors, squamates have likely utilized over-land range expansion, land-bridge colonization, and trans-oceanic dispersal. Tropical Gondwana and Eurasia hold more ancient lineages than the Holarctic (Rhineuridae being a major exception), and some asymmetries in colonization (e.g., to North America from Eurasia during the Cenozoic through Beringia) deserve additional study. Future studies that incorporate fossil branches, rather than as node constraints, into the reconstruction can be used to explore this history further.


Subject(s)
Fossils , Animals , Phylogeny , Biological Evolution , Snakes/anatomy & histology , Snakes/classification , Snakes/genetics , Lizards/anatomy & histology , Lizards/genetics , Lizards/classification , Phylogeography , Europe , Asia
14.
PeerJ ; 12: e17353, 2024.
Article in English | MEDLINE | ID: mdl-38737736

ABSTRACT

A series of 12 contiguous caudal vertebrae of an ichthyodectiform fish from the Smoky Hill Chalk Member of the Niobrara Formation is described. The vertebral centra exhibit extensive overgrowth of pathological bone and there is additional pathological bone within the centra and intervertebral spaces, which together resulted in the coossification of most centra. The extent of the pathology is greatest on preural vertebrae 1-3 and decreases anteriorly, which suggests that the pathology began posteriorly and progressed anteriorly. In addition to the pathological overgrowth on bones, the specimen preserves features interpreted as calcified and/or ossified soft tissues associated with the neural and haemal canals. The pathologies are unlike previously described examples of bony pathologies in fish, and it is suggested that they resulted from combined bacterial and fungal infections. As the pathologies developed, they would have adversely impacted the fish's swimming and feeding abilities, and presumably eventually led to the fish's death.


Subject(s)
Fishes , Spine , Animals , Fishes/anatomy & histology , Kansas , Spine/pathology , Spine/anatomy & histology , Fossils , Fish Diseases/parasitology , Fish Diseases/pathology
15.
Proc Biol Sci ; 291(2023): 20232832, 2024 May.
Article in English | MEDLINE | ID: mdl-38747704

ABSTRACT

Asexual reproduction by means of splitting, also called fissiparity, is a common feature in some asterozoan groups, especially in ophiactid brittle stars. Most fissiparous brittle stars show six instead of the usual five rays, live as epibionts on host organisms, and use clonal fragmentation to rapidly colonize secluded habitats and effectively expand the margins of their distribution area. While the biology and ecology of clonal fragmentation are comparatively well understood, virtually nothing is known about the evolution and geological history of that phenomenon. Here, we describe an exceptional fossil of an articulated six-armed brittle star from the Late Jurassic of Germany, showing one body half in the process of regeneration, and assign it to the new species Ophiactis hex sp. nov. Phylogenetic inference shows that the fossil represents the oldest member of the extant family Ophiactidae. Because the Ophiactis hex specimen shows an original six-fold symmetry combined with a morphology typically found in epizoic ophiuroids, in line with recent fissiparous ophiactid relatives, we assume that the regenerating body half is an indication for fissiparity. Ophiactis hex thus shows that fissiparity was established as a means of asexual reproduction in asterozoan echinoderms by the Late Jurassic.


Subject(s)
Echinodermata , Fossils , Phylogeny , Reproduction, Asexual , Animals , Fossils/anatomy & histology , Echinodermata/anatomy & histology , Echinodermata/physiology , Biological Evolution , Germany
16.
Proc Biol Sci ; 291(2023): 20240537, 2024 May.
Article in English | MEDLINE | ID: mdl-38747705

ABSTRACT

The noasaurid ceratosaur Kiyacursor longipes gen. et sp. nov. is described based on a fragmentary skeleton including cervical vertebra, pectoral girdle, humerus and hind limbs from the Lower Cretaceous (Aptian) Ilek Formation at Shestakovo 1 locality in Western Siberia, Russia. This is the first ceratosaur from the Early Cretaceous of Asia, extending the stratigraphic range of Ceratosauria by 40 Myr on that continent. Kiyacursor shares unique hind limb proportions with Elaphrosaurus and Limusaurus, suggesting improved cursorial ability. These taxa show an ostrich-like specialization of the pes, with a large third metatarsal and greatly reduced second metatarsal. By contrast, all other fast running non-avian theropod dinosaurs have an arctometatarsalian pes, with the third metatarsal strongly reduced proximally. The new taxon lived in the Early Cretaceous ecosystem containing a number of other Jurassic relics, such as stem salamanders, protosuchian and shartegosuchid crocodyliforms, tritylodontid synapsids and docodontan mammaliaforms.


Subject(s)
Dinosaurs , Fossils , Animals , Dinosaurs/anatomy & histology , Dinosaurs/classification , Fossils/anatomy & histology , Siberia , Biological Evolution
17.
BMC Ecol Evol ; 24(1): 59, 2024 May 10.
Article in English | MEDLINE | ID: mdl-38730384

ABSTRACT

The study of thirty-two shed crowns from the Portezuelo Formation (middle Turonian-late Coniacian) at the Sierra del Portezuelo locality, reveals six distinct tooth morphotypes identified through cladistic, discriminant, and cluster analyses. Two morphotypes were identified as belonging to Megaraptoridae, three to Abelisauridae, one to Abelisauroidea, and one to Alvarezsauridae. Additionally, two of the morphotypes exhibit a combination of dental features typically found in megaraptorid and abelisauridtheropods. These results suggest a greater diversity of theropods in the original ecosystem than previously thought, including the presence of a second morphotype of megaraptorid and alvarezsaurid previously undocumented in this formation. Furthermore, the existence of Morphotype 6 indicates the potential coexistence of medium-sized abelisauroids alongside larger abelisaurids in the same ecosystem. These findings underscore the importance of future expeditions to the Sierra del Portezuelo locality to further our understanding of these previously unknown theropod species.


Subject(s)
Fossils , Tooth , Animals , Tooth/anatomy & histology , Biodiversity , Argentina , Phylogeny
18.
Commun Biol ; 7(1): 568, 2024 May 14.
Article in English | MEDLINE | ID: mdl-38745082

ABSTRACT

Interpretations of Late Pleistocene hominin adaptative capacities by archaeologists have focused heavily on their exploitation of certain prey and documented contemporary behaviours for these species. However, we cannot assume that animal prey-taxa ecology and ethology were the same in the past as in the present, or were constant over archaeological timescales. Sequential isotope analysis of herbivore teeth has emerged as a particularly powerful method of directly reconstructing diet, ecology and mobility patterns on sub-annual scales. Here, we apply 87Sr/86Sr isotope analysis, in combination with δ18O and δ13C isotope analysis, to sequentially sampled tooth enamel of prevalent herbivore species that populated Europe during the Last Glacial Period, including Rangifer tarandus, Equus sp. and Mammuthus primigenius. Our samples come from two open-air archaeological sites in Central Germany, Königsaue and Breitenbach, associated with Middle Palaeolithic and early Upper Palaeolithic cultures, respectively. We identify potential inter- and intra-species differences in range size and movement through time, contextualised through insights into diet and the wider environment. However, homogeneous bioavailable 87Sr/86Sr across large parts of the study region prevented the identification of specific migration routes. Finally, we discuss the possible influence of large-herbivore behaviour on hominin hunting decisions at the two sites.


Subject(s)
Carbon Isotopes , Herbivory , Animals , Carbon Isotopes/analysis , Fossils , Hominidae/physiology , Strontium Isotopes/analysis , Archaeology , Europe , Animal Migration , Dental Enamel/chemistry , Diet , Germany , Oxygen Isotopes/analysis
19.
Sci Adv ; 10(20): eadl6717, 2024 May 17.
Article in English | MEDLINE | ID: mdl-38748800

ABSTRACT

Documenting the seasonal temperature cycle constitutes an essential step toward mitigating risks associated with extreme weather events in a future warmer world. The mid-Piacenzian Warm Period (mPWP), 3.3 to 3.0 million years ago, featured global temperatures approximately 3°C above preindustrial levels. It represents an ideal period for directed paleoclimate reconstructions equivalent to model projections for 2100 under moderate Shared Socioeconomic Pathway SSP2-4.5. Here, seasonal clumped isotope analyses of fossil mollusk shells from the North Sea are presented to test Pliocene Model Intercomparison Project 2 outcomes. Joint data and model evidence reveals enhanced summer warming (+4.3° ± 1.0°C) compared to winter (+2.5° ± 1.5°C) during the mPWP, equivalent to SSP2-4.5 outcomes for future climate. We show that Arctic amplification of global warming weakens mid-latitude summer circulation while intensifying seasonal contrast in temperature and precipitation, leading to an increased risk of summer heat waves and other extreme weather events in Europe's future.


Subject(s)
Global Warming , Seasons , Europe , Temperature , Animals , Climate Change , Fossils , Climate Models
20.
PeerJ ; 12: e16541, 2024.
Article in English | MEDLINE | ID: mdl-38774542

ABSTRACT

In the Western Scheldt Estuary near the Belgian-Dutch border, middle to late Eocene strata crop out at the current seafloor. Most vertebrae of large Eocene basilosaurid taxa from this area were previously described in several papers. They represent three morphotypes: elongated vertebrae of a large species of Pachycetus (Morphotype 1b), a not-elongated vertebra of a large 'dorudontid' basilosaurid (Morphotype 2) and 'shortened' vertebrae of a new, unnamed taxon (Morphotype 3). This article deals with a still undescribed, smaller vertebra, NMR-16642, from this site. Our first aim was to date it by dinoflagellate cysts in adhering sediments. Yielding an age of about 38 Ma, it is one of the very few remains of basilosaurids from Europe, of which the age could be assessed with reasonable certainty. The vertebra, Morphotype 1a, is assigned to a small species of Pachycetus. High-quality CT scans are used to differentiate between NMR-16642, Morphotype 1a, and the large species of Pachycetus, Morphotype 1b. Another aim of this paper is to investigate the inner structure and vascularity of the study vertebra and that of the other morphotypes (1b, 2, 3) from this area by using high-quality CT scans. Notwithstanding differences in size, shape and compactness, the vertebral inner structure with a multi-layered cortex of periosteal bone, surrounding two cones of endosteal bone appears to be basically similar in all morphotypes. Apparently, this inner structure reflects the ontogenetic vertebral growth. An attempt to reconstruct the vascularity of the vertebrae reveals a remarkable pattern of interconnected vascular systems. From the dorsal and, if present, ventral foramina, vascular canals are running to a central vascular node. From this node a system of vascular canals goes to the epiphyseal ends, giving rise to separate systems for cortex and cones. It is the first time that the vascularity of vertebrae of archaeocetes is investigated.


Subject(s)
Fossils , Spine , Animals , Spine/anatomy & histology , Spine/blood supply , North Sea , Dinosaurs/anatomy & histology , Dinosaurs/classification , Tomography, X-Ray Computed
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