Ben Creisler
Some recent non-dino papers:
Free pdf:
Free pdf:
https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.6411Realized trophic niches of predators are often characterized along a oneâdimensional range in predatorâprey body mass ratios. This prey range is constrained by an âenergy limitâ and a âsubdue limitâ toward small and large prey, respectively. Besides these body mass ratios, maximum speed is an additional key component in most predatorâprey interactions.
Here, we extend the concept of a oneâdimensional prey range to a twoâdimensional prey space by incorporating a humpâshaped speedâbody mass relation. This new âspeed limitâ additionally constrains trophic niches of predators toward fast prey.
To test this concept of twoâdimensional prey spaces for different hunting strategies (pursuit, group, and ambush predation), we synthesized data on 63 terrestrial mammalian predatorâprey interactions, their body masses, and maximum speeds.
We found that pursuit predators hunt smaller and slower prey, whereas group hunters focus on larger but mostly slower prey and ambushers are more flexible. Group hunters and ambushers have evolved different strategies to occupy a similar trophic niche that avoids competition with pursuit predators. Moreover, our concept suggests energetic optima of these hunting strategies along a body mass axis and thereby provides mechanistic explanations for why there are no small group hunters (referred to as âmicroâlionsâ) or megaâcarnivores (referred to as âmegaâcheetahsâ).
Our results demonstrate that advancing the concept of prey ranges to prey spaces by adding the new dimension of speed will foster a new and mechanistic understanding of predator trophic niches and improve our predictions of predatorâprey interactions, food web structure, and ecosystem functions.
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We compared the osteology of the late Eocene to early Miocene penguinâlike Plotopteridae from the North Pacific Basin with that of Paleocene stem group representatives of the Sphenisciformes and identified previously unrecognized similarities and differences. New data on the osteology of plotopterids, like the shape of the caudal end of the mandible, support a position of plotopterids outside the Suloidea, the clade formed by Sulidae, Phalacrocoracidae, and Anhingidae. However, as assumed by previous authors, the diving adaptations of plotopterids and sphenisciforms are likely to have evolved independently, and the resemblances in different parts of the postcranial skeleton therefore constitute one of the more striking examples of parallelism among tetrapods. We note that close relatives of both plotopterids and penguins forage by plunge diving. Whereas underwater locomotion of diving birds with a swimming ancestor is usually driven by the feet, we hypothesize that plotopterids and other wingâpropelled divers are more likely to have had volant ancestors that initiated diving by shallow plunges into the sea.
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Not paleo as such (some fossil taxa) but it's free...
Free pdf:
R. Terry Chesser, Shawn M. Billerman, Kevin J. Burns, Carla Cicero, Jon L. Dunn, Andrew W. Kratter, Irby J. Lovette, Nicholas A. Mason, Pamela C. Rasmussen, J. V. Remsen, Jr., Douglas F. Stotz & Kevin Winker (2020)
Sixty-first Supplement to the American Ornithological Societyâs Check-list of North American Birds.
The Auk, ukaa030
doi:
https://doi.org/10.1093/auk/ukaa030https://academic.oup.com/auk/article/doi/10.1093/auk/ukaa030/5865308?searchresult=1
This is the 20th supplement since publication of the 7th edition of the Check-list of North American Birds (American Ornithologists' Union [AOU] 1998). It summarizes decisions made between April 15, 2019 and April 15, 2020 by the American Ornithological Societyâs (formerly American Ornithologistsâ Unionâs) Committee on Classification and NomenclatureâNorth and Middle America. The Committee has continued to operate in the manner outlined in the 42nd Supplement (Banks et al. 2000). During the past year, Shawn M. Billerman and Nicholas A. Mason were added to the committee.
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Free pdf:
Serjoscha W. Evers, Yann Rollot & Walter G. Joyce (2020)
Cranial osteology of the Early Cretaceous turtle Pleurosternon bullockii (Paracryptodira: Pleurosternidae).
PeerJ 8:e9454
doi:
https://doi.org/10.7717/peerj.9454https://peerj.com/articles/9454/Â
Pleurosternon bullockii is a turtle from the Early Cretaceous of Europe known from numerous postcranial remains. Only one skull has so far been referred to the species. Pleurosternon bullockii belongs to a group of turtles called pleurosternids, which is thought to include several poorly known taxa from the Late Jurassic and Early Cretaceous of Europe and North America. Pleurosternids and baenids, a group of North American turtles that lived from the Late Cretaceous to the Eocene, define a clade called Paracryptodira. Additionally, Paracryptodira likely includes compsemydids, and, potentially, helochelydrids. Character support for Paracryptodira is relatively weak, and many global phylogenetic studies fail to support paracryptodiran monophyly altogether. Proposed paracryptodiran synapomorphies are largely cranial, despite the poor characterization of pleurosternid cranial material. In addition to their questionable monophyly, the global position of paracryptodires is debated. Early studies suggest crown-turtle affinities, but most phylogenies find them as stem-turtles, irrespective of their monophyly. Here, we document the cranial osteology of Pleurosternon bullockii with the use of three-dimensional models derived from segmenting high-resolution X-ray micro-computed tomography (CT) scans. Pleurosternon bullockii has a primitive basipterygoid region of the skull, but a cryptodire-like acustico-jugular region. A surprising number of similarities with pleurodires exist, particularly in the laterally expanded external process of the pterygoid and in the posterior orbital wall. Our observations constitute an important step toward a phylogenetic re-evaluation of Paracryptodira.
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Free pdf:
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Extant and extinct reptiles exhibit numerous combinations of tooth implantation and attachment. Tooth implantation ranges from those possessing roots and lying within a socket (thecodonty), to teeth lying against the lingual wall of the jawbone (pleurodonty), to teeth without roots or sockets that are attached to the apex of the marginal jawbones (acrodonty). Attachment may be ligamentous (gomphosis) or via fusion (ankylosis). Generally speaking, adaptative reasonings are proposed as an underlying driver for evolutionary changes in some forms of tooth implantation and attachment. However, a substantiated adaptive hypothesis is lacking for the state of acrodont ankylosis that is seen in several lineages of Lepidosauria, a clade that is plesiomorphically pleurodont. The convergent evolution of acrodont ankylosis in several clades of lepidosaurs suggests a selective pressure shaped the evolution of the trait. We hypothesize that acrodont ankylosis as seen in Acrodonta and Sphenodon punctatus, is an adaptation either resulting from or allowing for a stronger bite force. We analyzed bite force data gathered from the literature to show that those taxa possessing acrodont dentition possess a stronger bite force on average than those taxa with pleurodont dentition. Dietary specialists with pleurodont dentition may also possess relatively high bite forces, though body size may also play a role in their ability to bite hard. Furthermore, our results have implications for the evolution of acrodont ankylosis and potential behaviors related to strong bite force that influenced the evolution of acrodonty within Acrodonta and Rhynchocephalia.
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