Ben Creisler
Some recent non-dino papers:
Jacamatia luberonensis gen. et sp. nov.
Together, puffbirds (Bucconidae) and jacamars (Galbulidae) form the suborder Galbulae, sister group of all other Piciformes. Hitherto, the Galbulae had no ascertained pre-Pleistocene fossil record, and all previous alleged candidates have been refuted, except possibly the Sylphornithidae. Here we describe a wing of a tiny fossil bird from the early Oligocene of the Luberon region (southern France), which we assign to the Galbulae, as a new genus and species. Several characters, especially of the ulna and wing phalanx 1 of digit II, exclude the Passeriformes and Zygodactylidae, and indicate a representative of the Piciformes. Among Piciformes, absence of papillae remigales caudales and several characters of the wing phalanx 1 of digit II make it possible to assign the fossil to the Galbulae, and exclude all other clades. The fossil Sylphornithidae, with the carpometacarpus of Sylphornis being available, show some similarity with the Luberon fossil. The combination of features of the wing elements leads to the placement of the new fossil as stem Galbulae, and tentatively within the family Sylphornithidae. As such, it fills a gap and permits to better assign the whole enigmatic tiny sylphornithids, otherwise essentially known from leg bones. This yields the first firm pre-Pleistocene fossil record for the Galbulae. Today, both the Bucconidae and Galbulidae live exclusively in tropical America. The presence of stem Galbulae in the Oligocene of Europe, and probably the late Eocene, is a new example of a present-day Neotropical clade that had stem representatives in the Paleogene of Europe.
===
===
The vertebrate head as a major novelty is directly linked to the evolutionary success of the vertebrates. Sequential information on the embryonic pattern of cartilaginous head development are scarce, but important for the understanding of its evolution. In this study, we use the oriental fire bellied toad, Bombina orientalis, a basal anuran to investigate the sequence and timing of larval cartilaginous development of the head skeleton from the appearance of mesenchymal Anlagen in postâneurulation stages until the premetamorphic larvae. We use different methodological approaches like classic histology, clearing and staining, and antibody staining to examine the larval skeletal morphology. Our results show that in contrast to other vertebrates, the ceratohyals are the first centers of chondrification. They are followed by the palatoquadrate and the basihyal. The latter later fuses to the ceratohyal and the branchial basket. Anterior elements like Meckel's cartilage and the rostralia are delayed in development and alter the ancestral anterior posterior pattern observed in other vertebrates. The ceratobranchials IâIV, components of the branchial basket, follow this strict anteriorâposterior pattern of chondrification as reported in other amphibians. Chondrification of different skeletal elements follows a distinct pattern and the larval skeleton is nearly fully developed at Gosner Stage 28. We provide baseline data on the pattern and timing of early cartilage development in a basal anuran species, which may serve as guidance for further experimental studies in this species as well as an important basis for the understanding of the evolutionary changes in head development among amphibians and vertebrates.
===
Significance
Ballistic tongue projection in lungless salamanders displays both extreme performance and thermal robustness, with the power of projection far exceeding the available muscle power even at low body temperatures. Our comparative analysis reveals that relatively minor changes in the musculoskeletal morphology of the tongue apparatus and in the timing of muscle activation have, through evolutionary time, transformed a muscle-powered system with modest performance and high thermal sensitivity into a spring-powered system with extreme performance and thermal robustness, in parallel in both major groups of this largest family of salamanders. High performance and thermal robustness evolve together, indicating they are both properties of the same elastic-recoil, âbow-and-arrowâ mechanism. Similar evolutionary patterns may be found in other ectothermic animals with extreme performance.
Abstract
The evolution of ballistic tongue projection in plethodontid salamanders--a high-performance and thermally robust musculoskeletal system--is ideal for examining how the components required for extreme performance in animal movement are assembled in evolution. Our comparative data on whole-organism performance measured across a range of temperatures and the musculoskeletal morphology of the tongue apparatus were examined in a phylogenetic framework and combined with data on muscle contractile physiology and neural control. Our analysis reveals that relatively minor evolutionary changes in morphology and neural control have transformed a muscle-powered system with modest performance and high thermal sensitivity into a spring-powered system with extreme performance and functional robustness in the face of evolutionarily conserved muscle contractile physiology. Furthermore, these changes have occurred in parallel in both major clades of this largest family of salamanders. We also find that high-performance tongue projection that exceeds available muscle power and thermal robustness of performance coevolve, both being emergent properties of the same elastic-recoil mechanism. Among the taxa examined, we find muscle-powered and fully fledged elastic systems with enormous performance differences, but no intermediate forms, suggesting that incipient elastic mechanisms do not persist in evolutionary time. A growing body of data from other elastic systems suggests that similar coevolution of traits may be found in other ectothermic animals with high performance, particularly those for which thermoregulation is challenging or ecologically costly.