A partial plesiosaurian braincase from the Upper Cretaceous of Sweden

A partial exoccipital-opisthotic from the uppermost lower Campanian (Upper Cretaceous) of the Åsen locality, Kristianstad Basin, southernmost Sweden, is described and illustrated. The fossil represents the first braincase element of a plesiosaur found in Sweden. It includes the chamber for the ampulla and utriculus, openings for the caudal vertical and horizontal semicircular canals, and four foramina for cranial nerves. The incomplete braincase can be referred to an elasmosaurid plesiosaur, and closely resembles the exoccipital-opisthotic of Libonectes morgani and a referred specimen of Aristonectes parvidens. Although we discuss putative postcranial material of the elasmosaurid subfamily Aristonectinae in the uppermost lower Campanian of southernmost Sweden, the exoccipital-opisthotic from Åsen most likely belongs to a juvenile individual of a non-aristonectine elasmosaur

Southern higher-latitude lamniform sharks track mid-Cretaceous environmental change

The mid-Cretaceous (Albian and Cenomanian, 113–93.9 Myr) marked a transformative interval of shark evolution during which lamniforms (mackerel sharks) diversified as dominant marine predators. Yet, their radiation dynamics relative to major biotic turnovers delimiting the Albian–Cenomanian and Cenomanian–Turonian boundaries are incompletely understood. Here, we use the high-resolution dental fossil record of lamniforms to track changing morphological disparity and tooth size through a succession of mid-Cretaceous shark assemblages from higher-palaeolatitude (up to ∼ 58°S) settings in Australia. Our geometric morphometric analyses and evolutionary model fitting reveal stable disparity throughout the late Albian–late Cenomanian. By contrast, lamniform disparity increased in the early Turonian, which might reflect local habitat differences and/or intraspecific variability through heterodonty. Nevertheless, clade-specific partial disparity increases are evident among small-bodied carchariids, and couple with a trend towards larger teeth as a proxy for body-size in coeval anacoracids. We correlate these signals with recovery after the Oceanic Anoxic Event 2, which severely disrupted latest Cenomanian marine ecosystems and apparently instigated disjunct responses in shark communities occupying epeiric versus outer neritic environments

Vertebral morphology, dentition, age, growth, and ecology of the large lamniform shark Cardabiodon ricki

Cardabiodon ricki and Cardabiodon venator were large lamniform sharks with a patchy but global distribution in the Cenomanian and Turonian. Their teeth are generally rare and skeletal elements are less common. The centra of Cardabiodon ricki can be distinguished from those of other lamniforms by their unique combination of characteristics: medium length, round articulating outline with a very thick corpus calcareum, a corpus calcareum with a laterally flat rim, robust radial lamellae, thick radial lamellae that occur in low density, concentric lamellae absent, small circular or subovate pores concentrated next to each corpus calcareum, and papillose circular ridges on the surface of the corpus calcareum. The large diameter and robustness of the centra of two examined specimens suggest that Cardabiodon was large, had a rigid vertebral column, and was a fast swimmer. The sectioned corpora calcarea show both individuals deposited 13 bands (assumed to represent annual increments) after the birth ring. The identification of the birth ring is supported in the holotype of Cardabiodon ricki as the back-calculated tooth size at age 0 is nearly equal to the size of the smallest known isolated tooth of this species. The birth ring size (5–6.6 mm radial distance [RD]) overlaps with that of Archaeolamna kopingensis (5.4 mm RD) and the range of variation of Cretoxyrhina mantelli (6–11.6 mm RD) from the Smoky Hill Chalk, Niobrara Formation. The revised, reconstructed lower jaw dentition of the holotype of Cardabiodon ricki contains four anterior and 12 lateroposterior files. Total body length is estimated at 5.5 m based on 746 mm lower jaw bite circumference reconstructed from associated teeth of the holotype

Cenomanian-Campanian (Late Cretaceous) mid-palaeolatitude sharks of Cretalamna appendiculata type

The type species of the extinct lamniform genus Cretalamna, C. appendiculata, has been assigned a 50 Ma range (Albian-Ypresian) by a majority of previous authors. Analysis of a partly articulated dentition of a Cretalamna from the Smoky Hill Chalk, Kansas, USA (LACM 128126) and isolated teeth of the genus from Cenomanian to Campanian strata of Western Australia, France, Sweden, and the Western Interior of North America, indicates that the name of the type species, as applied to fossil material over the last 50 years, represents a large species complex. The middle Cenomanian part of the Gearle Siltstone, Western Australia, yielded C. catoxodon sp. nov. and "Cretalamna" gunsoni. The latter, reassigned to the new genus Kenolamna, shares several dental features with the Paleocene Palaeocarcharodon. Early Turonian strata in France produced the type species C. appendiculata, C. deschutteri sp. nov., and C. gertericorum sp. nov. Cretalamna teeth from the late Coniacian part of the Smoky Hill Chalk in Kansas are assigned to C. ewelli sp. nov., whereas LACM 128126, of latest Santonian or earliest Campanian age, is designated as holotype of C. hattini sp. nov. Early Campanian deposits in Sweden yielded C. borealis and C. sarcoportheta sp. nov. A previous reconstruction of the dentition of LACM 128126 includes a posteriorly situated upper lateroposterior tooth, with a distally curved cusp, demonstrably misplaced as a reduced upper "intermediate" tooth. As originally reconstructed, the dentition resembled that of cretoxyrhinids (sensu stricto) and lamnids. Tooth morphology, however, indicates an otodontid affinity for Cretalamna. The root is typically the most diagnostic feature on an isolated Cretalamna tooth. This porous structure is commonly abraded and/or corroded and, consequently, many collected Cretalamna teeth are indeterminable at species level

Anacoracid sharks and calcareous nannofossil stratigraphy of the mid-Cretaceous ‘upper’ Gearle Siltstone and Haycock Marl in the lower Murchison River area, Western Australia

Extensive bulk sampling over the past 20 years and greatly improved stratigraphic control permitted a meaningful revision of previously described anacoracid sharks from the ‘upper’ Gearle Siltstone and lower Haycock Marl in the lower Murchison River area, Western Australia. Isolated teeth of anacoracids are rare in the lower three (Beds 1–3) of four stratigraphic units of the ‘upper’ Gearle Siltstone but relatively common in the uppermost layer (Bed 4) and in the lower part of the overlying Haycock Marl. On the basis of calcareous nannofossils, Beds 1 and 2 of the ‘upper’ Gearle Siltstone can be placed in the uppermost upper Albian calcareous nannofossil Subzone CC9b whereas Bed 3 can be referred to the lowermost Cenomanian CC9c Subzone. Bed 1 yielded fragments of strongly serrated anacoracid teeth as well as a single, smooth-edged tooth. The samples from Beds 2 and 3 contained a few small fragments of serrated anacoracid teeth. Bed 4 is barren of calcareous nannofossils but the presence of a dentally advanced tooth of the cosmopolitan lamniform genus Cretoxyrhina in combination with the age of the overlying Haycock Marl indicate deposition within the younger half of the Cenomanian. The unit produced teeth of two anacoracids; Squalicorax acutus sp. nov. and S. bazzii sp. nov. The basal, laminated part of the Haycock Marl is placed in the uppermost upper Cenomanian part of CC10b. It yielded Squalicorax mutabilis sp. nov. and S. aff. S. bernardezi. Exceptionally well-preserved teeth of the former species span a 5:1 size ratio range for teeth of comparable jaw position. The teeth reveal strong ontogenetic heterodonty with a large increase in the relative size of the main cusp with age and the transition from a vertical distal heel of the crown in very young juveniles to a sub-horizontal, well demarcated heel in ‘adult’ teeth. An isolated phosphatic lens in the lower part of the Haycock Marl produced calcareous nannofossils indicative of the CC10b SubZone, most likely the lowermost lower Turonian part. It contains teeth of Squalicorax mutabilis sp. nov., S. aff. S. bernardezi, and S. sp. C

A new clade of putative plankton-feeding sharks from the Upper Cretaceous of Russia and the United States

<div><p>ABSTRACT</p><p><i>Eorhincodon casei</i> from Russia and <i>Megachasma comanchensis</i> from the United States are two Cretaceous taxa initially described as putative planktivorous elasmobranchs, but the type specimens of these two taxa were subsequently reinterpreted to represent taphonomically abraded teeth of an odontaspidid, <i>Johnlongia</i> Siverson (Lamniformes: Odontaspididae). Here, we redescribe the type materials of ‘<i>E. casei</i>’ and ‘<i>M. comanchensis</i>’ and describe additional specimens of these species from other Late Cretaceous localities in Russia and the United States. These specimens demonstrate that (1) the two fossil taxa are valid species; (2) they warrant the establishment of a new genus of presumed planktivorous sharks, <i>Pseudomegachasma</i>, gen. nov., to accommodate the two species; and (3) the new genus is sister to <i>Johnlongia</i> and together constitute a new subfamily Johnlonginae, subfam. nov., tentatively placed in the family Odontaspididae sensu stricto. This taxonomic placement indicates that the putative planktivorous clade was derived from a presumed piscivorous form (<i>Johnlongia</i>), with an implication that <i>Pseudomegachasma</i>, gen. nov., evolved a plankton-eating habit independent of the four known planktivorous elasmobranch clades (Rhincodontidae, Megachasmidae, Cetorhinidae, and Mobulidae). It also indicates that planktivorous diets evolved independently at least three times in the order Lamniformes (i.e., Megachasmidae, Cetorhinidae, and Odontaspididae), and more significantly, <i>Pseudomegachasma</i>, gen. nov., would represent the oldest known plankton-feeding elasmobranch in the fossil record. The present fossil record suggests that <i>Pseudomegachasma</i>, gen. nov., evolved in a relatively shallow-water environment in Russia in the early Cenomanian or earlier and subsequently migrated to the North American Western Interior Seaway by the mid-Cenomanian.</p><p>http://zoobank.org/urn:lsid:zoobank.org:pub:D5D0400FD438-4A95-8301-DD47991572F6</p><p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP</p></div

Anacoracid sharks and calcareous nannofossil stratigraphy of the mid-Cretaceous ‘upper’ Gearle Siltstone and Haycock Marl in the lower Murchison River area, Western Australia

<p> Siversson, M., Cook, T.D., Ryan, H.E., Watkins, D.K., Tatarnic, N.J., Downes, P.J. & Newbrey, M.G. 5 June 2018. Anacoracid sharks and calcareous nannofossil stratigraphy of the mid-Cretaceous Gearle Siltstone and Haycock Marl in the lower Murchison River area, Western Australia. <i>Alcheringa</i> 43, 85–113.</p> <p>Extensive bulk sampling over the past 20 years and greatly improved stratigraphic control permitted a meaningful revision of previously described anacoracid sharks from the ‘upper’ Gearle Siltstone and lower Haycock Marl in the lower Murchison River area, Western Australia. Isolated teeth of anacoracids are rare in the lower three (Beds 1–3) of four stratigraphic units of the ‘upper’ Gearle Siltstone but relatively common in the uppermost layer (Bed 4) and in the lower part of the overlying Haycock Marl. On the basis of calcareous nannofossils, Beds 1 and 2 of the ‘upper’ Gearle Siltstone can be placed in the uppermost upper Albian calcareous nannofossil Subzone CC9b whereas Bed 3 can be referred to the lowermost Cenomanian CC9c Subzone. Bed 1 yielded fragments of strongly serrated anacoracid teeth as well as a single, smooth-edged tooth. The samples from Beds 2 and 3 contained a few small fragments of serrated anacoracid teeth. Bed 4 is barren of calcareous nannofossils but the presence of a dentally advanced tooth of the cosmopolitan lamniform genus <i>Cretoxyrhina</i> in combination with the age of the overlying Haycock Marl indicate deposition within the younger half of the Cenomanian. The unit produced teeth of two anacoracids; <i>Squalicorax acutus</i> sp. nov. and <i>S</i>. <i>bazzii</i> sp. nov. The basal, laminated part of the Haycock Marl is placed in the uppermost upper Cenomanian part of CC10b. It yielded <i>Squalicorax mutabilis</i> sp. nov. and <i>S</i>. aff. <i>S</i>. <i>bernardezi</i>. Exceptionally well-preserved teeth of the former species span a 5:1 size ratio range for teeth of comparable jaw position. The teeth reveal strong ontogenetic heterodonty with a large increase in the relative size of the main cusp with age and the transition from a vertical distal heel of the crown in very young juveniles to a sub-horizontal, well demarcated heel in ‘adult’ teeth. An isolated phosphatic lens in the lower part of the Haycock Marl produced calcareous nannofossils indicative of the CC10b SubZone, most likely the lowermost lower Turonian part. It contains teeth of <i>Squalicorax mutabilis</i> sp. nov., <i>S</i>. aff. <i>S</i>. <i>bernardezi</i>, and <i>S</i>. sp. C.</p> <p><i>Mikael Siversson* [</i><i>mikael</i>.<i>siversson@museum</i>.<i>wa</i>.<i>gov</i>.<i>au</i><i>], Helen E</i>. <i>Ryan [</i><i>helen</i>.<i>ryan@museum</i>.<i>wa</i>.<i>gov</i>.<i>au</i><i>] and Peter Downes [</i><i>peter</i>.<i>downes@museum</i>.<i>wa</i>.<i>gov</i>.<i>au</i><i>] Department of Earth and Planetary Sciences</i>, <i>Western Australian Museum</i>, <i>49 Kew Street</i>, <i>Welshpool</i>, <i>Western Australia 6106</i>, <i>Australia</i>; <i>David K</i>. <i>Watkins [</i><i>dwatkins@unl</i>.<i>edu</i><i>] Department of Earth and Atmospheric Sciences</i>, <i>University of Nebraska</i>, <i>Lincoln</i>, <i>NE 68588</i>, <i>USA</i>; <i>Todd D</i>. <i>Cook [</i><i>tdc15@psu</i>.<i>edu</i><i>] School of Science</i>, <i>Penn State Behrend</i>, <i>4205 College Drive</i>, <i>Erie</i>, <i>PA 16563</i>, <i>USA</i>; <i>Nikolai J</i>. <i>Tatarnic† [</i><i>nikolai</i>.<i>tatarnic@museum</i>.<i>wa</i>.<i>gov</i>.<i>au</i><i>] Department of Terrestrial Zoology</i>, <i>Western Australian Museum</i>, <i>49 Kew Street</i>, <i>Welshpool</i>, <i>Western Australia 6106</i>, <i>Australia; Michael G</i>. <i>Newbrey‡ [</i><i>newbrey_michael@columbusstate</i>.<i>edu</i><i>] Department of Biology</i>, <i>Columbus State University</i>, <i>Columbus</i>, <i>GA 31907</i>-<i>5645</i>, <i>USA. *Also affiliated with: School of Molecular and Life Sciences</i>, <i>Curtin University</i>, <i>Kent Street</i>, <i>Bentley</i>, <i>WA 6102</i>, <i>Australia</i>. <i>†Also affiliated with: Centre for Evolutionary Biology</i>, <i>University of Western Australia</i>, <i>Crawley</i>, <i>Western Australia 6009</i>. <i>‡Also affiliated with: Canadian Fossil Discovery Centre</i>, <i>111-B Gilmour Street</i>, <i>Morden</i>, <i>Manitoba R6 M 1N9</i>, <i>Canada</i>.</p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:97D5131F-C0D5-4A7E-9C9A-0FDF13BFCBBB" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:97D5131F-C0D5-4A7E-9C9A-0FDF13BFCBBB</a></p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:act:5977DCC2-355C-4732-8B0A-4BD0EABBA8DE" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:act:5977DCC2-355C-4732-8B0A-4BD0EABBA8DE</a></p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:act:2D7C4147-B756-4434-847A-B0C1C6D167DF" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:act:2D7C4147-B756-4434-847A-B0C1C6D167DF</a></p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:act:33F3B55E-41E0-45B3-8296-A3B95C17B41D" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:act:33F3B55E-41E0-45B3-8296-A3B95C17B41D</a></p

Bone collagen from subtropical Australia is preserved for more than 50,000 years

Abstract Ancient protein studies have demonstrated their utility for looking at a wide range of evolutionary and historical questions. The majority of palaeoproteomics studies to date have been restricted to high latitudes with relatively temperate environments. A better understanding of protein preservation at lower latitudes is critical for disentangling the mechanisms involved in the deep-time survival of ancient proteins, and for broadening the geographical applicability of palaeoproteomics. In this study, we aim to assess the level of collagen preservation in the Australian fossil record. Collagen preservation was systematically examined using a combination of thermal age estimates, Fourier Transform Infrared Spectroscopy, Zooarchaeology by Mass Spectrometry, and protein deamidation calculations. We reveal unexpected subtropical survival of collagen in bones more than 50 thousand years old, showing that protein preservation can exceed chemical predictions of collagen survival in bone. These findings challenge preconceptions concerning the suitability of palaeoproteomics in subtropical Pleistocene environments. We explore potential causes of this unexpected result to identify the underlying mechanisms leading to this exceptional preservation. This study serves as a starting point for the analysis of ancient proteins in other (sub)tropical contexts, and at deeper timescales

Bone collagen from subtropical Australia is preserved for more than 50,000 years

Acknowledgements: We thank the Pibulmun Wadandi Yunungjarli people, and specifically the Webb family as Traditional Custodians in the Leeuwin-Naturaliste Region, the Wattandee and Yamatji Traditional Owners, the Barada Barna people of Bigerley, South Walker Creek, the Augusteyn family of Capricorn Caves, and the Darumbal people, for supporting our research. We are also grateful to Andrea Manica for sharing a beta version of the Pastclim R package with us, and to Simon Hickinbotham and Julie Wilson for assistance in using the Q2E R package. We would also like to thank Sandra Hebestreit for technical assistance with ZooMS extractions, and Erin Scott for technical assistance with FTIR measurements. We are also grateful to Kristine Korzow Richter for helpful discussions about the paper, and to the three anonymous reference whose thoughtful comments and suggestions have helped to improve the quality of the manuscript. This research was supported by the Max Planck Society, ARC Discovery Early Career Research Fellowships awarded to T.M. (DE150101597) and G.J.P. (DE120101533), an ARC Discovery Project awarded to G.J.P. (DP120101752), and an ERC award (Adv. 787282) awarded to M.J.C.Funder: Max-Planck-Gesellschaft (Max Planck Society); doi: https://doi.org/10.13039/501100004189AbstractAncient protein studies have demonstrated their utility for looking at a wide range of evolutionary and historical questions. The majority of palaeoproteomics studies to date have been restricted to high latitudes with relatively temperate environments. A better understanding of protein preservation at lower latitudes is critical for disentangling the mechanisms involved in the deep-time survival of ancient proteins, and for broadening the geographical applicability of palaeoproteomics. In this study, we aim to assess the level of collagen preservation in the Australian fossil record. Collagen preservation was systematically examined using a combination of thermal age estimates, Fourier Transform Infrared Spectroscopy, Zooarchaeology by Mass Spectrometry, and protein deamidation calculations. We reveal unexpected subtropical survival of collagen in bones more than 50 thousand years old, showing that protein preservation can exceed chemical predictions of collagen survival in bone. These findings challenge preconceptions concerning the suitability of palaeoproteomics in subtropical Pleistocene environments. We explore potential causes of this unexpected result to identify the underlying mechanisms leading to this exceptional preservation. This study serves as a starting point for the analysis of ancient proteins in other (sub)tropical contexts, and at deeper timescales.</jats:p