Influences of Domestication and Island Evolution on Dental Growth in Sheep

Funder: Department of Zoology, University of CambridgeFunder: Leverhulme Trust; doi: http://dx.doi.org/10.13039/501100000275Abstract: Domestication and island evolution can lead to changes of life history along the slow-fast gradient. Shifts of life history patterns, in turn, are potentially related to alterations of patterns and timing of tooth eruption. Schultz’s rule predicts an earlier eruption of molars relative to premolars as fecundity increases during the domestication process. On the other hand, evolution on a predator-free, resource limited island might lead to a generally slow life history and delayed tooth eruption, as in the Plio-Pleistocene Balearic caprine Myotragus. In this study, we investigate tooth eruption and its relation to life history in a unique sheep population that is an example of both domestication and island evolution: the ancient and feral Soay sheep (Ovis aries) of the St. Kilda archipelago, Scotland. Tooth eruption timing and sequence is investigated in a comparative framework featuring new data on other domestic sheep (O. aries), including European mouflon (O. a. musimon), as well as wild sheep (O. vignei, O. cycloceros, O. arkal, O. orientalis, O. ammon). These data indicate that the order of eruption is similar in wild and domestic sheep, despite the fundamental life history changes that came about with domestication. However, in contrast to other domestic sheep breeds, Soay sheep erupt their teeth at an absolute older age and also tend to grow more slowly, which resembles the evolutionary trend in island-adapted Myotragus. Despite these similarities, Soay sheep do not share the slow life history pattern inferred for Myotragus, highlighting the distinctive nature of tooth eruption in Soay sheep

Influences of Domestication and Island Evolution on Dental Growth in Sheep

Funder: Department of Zoology, University of CambridgeFunder: Leverhulme Trust; doi: http://dx.doi.org/10.13039/501100000275Abstract: Domestication and island evolution can lead to changes of life history along the slow-fast gradient. Shifts of life history patterns, in turn, are potentially related to alterations of patterns and timing of tooth eruption. Schultz’s rule predicts an earlier eruption of molars relative to premolars as fecundity increases during the domestication process. On the other hand, evolution on a predator-free, resource limited island might lead to a generally slow life history and delayed tooth eruption, as in the Plio-Pleistocene Balearic caprine Myotragus. In this study, we investigate tooth eruption and its relation to life history in a unique sheep population that is an example of both domestication and island evolution: the ancient and feral Soay sheep (Ovis aries) of the St. Kilda archipelago, Scotland. Tooth eruption timing and sequence is investigated in a comparative framework featuring new data on other domestic sheep (O. aries), including European mouflon (O. a. musimon), as well as wild sheep (O. vignei, O. cycloceros, O. arkal, O. orientalis, O. ammon). These data indicate that the order of eruption is similar in wild and domestic sheep, despite the fundamental life history changes that came about with domestication. However, in contrast to other domestic sheep breeds, Soay sheep erupt their teeth at an absolute older age and also tend to grow more slowly, which resembles the evolutionary trend in island-adapted Myotragus. Despite these similarities, Soay sheep do not share the slow life history pattern inferred for Myotragus, highlighting the distinctive nature of tooth eruption in Soay sheep

Influences of Domestication and Island Evolution on Dental Growth in Sheep

Domestication and island evolution can lead to changes of life history along the slow-fast gradient. Shifts of life history patterns, in turn, are potentially related to alterations of patterns and timing of tooth eruption. Schultz’s rule predicts an earlier eruption of molars relative to premolars as fecundity increases during the domestication process. On the other hand, evolution on a predatorfree, resource limited island might lead to a generally slow life history and delayed tooth eruption, as in the Plio-Pleistocene Balearic caprine Myotragus. In this study, we investigate tooth eruption and its relation to life history in a unique sheep population that is an example of both domestication and island evolution: the ancient and feral Soay sheep (Ovis aries) of the St. Kilda archipelago, Scotland. Tooth eruption timing and sequence is investigated in a comparative framework featuring new data on other domestic sheep (O. aries), including European mouflon (O. a. musimon), as well as wild sheep (O. vignei, O. cycloceros, O. arkal, O. orientalis, O. ammon). These data indicate that the order of eruption is similar in wild and domestic sheep, despite the fundamental life history changes that came about with domestication. However, in contrast to other domestic sheep breeds, Soay sheep erupt their teeth at an absolute older age and also tend to grow more slowly, which resembles the evolutionary trend in island-adapted Myotragus. Despite these similarities, Soay sheep do not share the slow life history pattern inferred for Myotragus, highlighting the distinctive nature of tooth eruption in Soay sheep. Keywords Tooth eruption . Ovis . Schultz’s rule . Soay shee

An avian femur from the Late Cretaceous of Vega Island, Antarctic Peninsula: Removing the record of cursorial landbirds from the Mesozoic of Antarctica

© 2019 West et al. In 2006, a partial avian femur (South Dakota School of Mines and Technology (SDSM) 78247) from the Upper Cretaceous (Maastrichtian) Sandwich Bluff Member of the López de Bertodano Formation of Sandwich Bluff on Vega Island of the northern Antarctic Peninsula was briefly reported as that of a cariamiform - A clade that includes extant and volant South American species and many extinct flightless and cursorial species. Although other authors have since rejected this taxonomic assignment, SDSM 78247 had never been the subject of a detailed description, hindering a definitive assessment of its affinities. Here we provide the first comprehensive description, illustration, and comparative study of this specimen. Comparison of characters that may be assessed in this femur with those of avian taxa scored in published character matrices refutes the inclusion of SDSM 78247 within Cariamiformes, instead supporting its assignment to a new, as-yet unnamed large-bodied species within the genus Vegavis, and therefore its referral to a clade of semiaquatic anseriforms. Important character states diagnostic of Vegavis + Polarornis include strong craniocaudal bowing of the femoral shaft, the presence of a distinct fossa just proximal to the fibular trochlea, and the broad and flat shape of the patellar sulcus. Referral to Vegavis is based on the presence of a distinctive proximocaudal fossa and distolateral scar. This genus was previously known only from Vegavis iaai, a smaller-bodied taxon from the same locality and stratigraphic unit. Our reassignment of SDSM 78247 to Vegavis sp. removes the record of cariamiform landbirds from the Antarctic Cretaceous

New evidence of a Campanian age for the Cretaceous fossil-bearing strata of Cape Marsh, Robertson Island, Antarctica

Cape Marsh, located on the eastern end of Robertson Island to the east of the Antarctic Peninsula, exposes an isolated outcrop of Upper Cretaceous sedimentary strata. The outcrop is approximately 120 km southwest of the much better-studied exposures of similar age on and around James Ross Island (JRI): as such, its remoteness has complicated logistical access to the site and hindered geologic correlations on a regional scale. Here we present the results of fieldwork conducted in 2016 that yielded a more diverse invertebrate fossil assemblage than had been previously recognized, in addition to new U-Pb detrital zircon and magnetostratigraphic data. The invertebrate fauna, particularly the ammonites and inoceramids, support a biostratigraphic correlation of the upper Cape Marsh strata to Ammonite Assemblage 7 previously established on JRI. Detrital zircon U-Pb analysis conducted on a sandstone sample from the same strata indicates a maximum depositional age of 74.2 +/- 1.1 Ma, and magnetostratigraphic interpretation of the lower strata suggest a normal magnetochron. These results are all consistent with a Campanian age for the deposition of the upper strata at Cape Marsh, and deposition during magnetochron C33N for the lower layers. However, a slight age inconsistency between the biostratigraphic correlation and the detrital zircon-derived maximum depositional age may imply that the fossils are reworked. Regardless, these new data allow us to correlate the strata at Cape Marsh to the Santa Marta and Rabot formations (or possibly the lower part of the Snow Hill Island Formation) in the northern part of the James Ross Basin

New evidence of a Campanian age for the Cretaceous fossil-bearing strata of Cape Marsh, Robertson Island, Antarctica

Cape Marsh, located on the eastern end of Robertson Island to the east of the Antarctic Peninsula, exposes an isolated outcrop of Late Cretaceous sedimentary strata. The outcrop is approximately 120 km southwest of the much better-studied exposures of similar age on and around James Ross Island (JRI); as such, its remoteness has complicated both logistical access to the site and hindered geologic correlations on a regional scale. Here we present the results of fieldwork conducted in 2016 that yielded a more diverse invertebrate fossil assemblage than had been previously recognized, in addition to new detrital zircon (U-Pb) and magnetostratigraphic data. The invertebrate fauna, particularly the ammonites and inoceramids, support a biostratigraphic correlation of the upper Cape Marsh strata to Ammonite Assemblage 7 previously established on JRI. U-Pb analysis conducted on a sandstone sample from the same strata indicates a maximum depositional age of 74.2 ± 1.1 Ma, and magnetostratigraphic interpretation of the lower strata suggest a normal magnetochron. These results are all consistent with a Campanian age for the deposition of the upper strata at Cape Marsh, and deposition during magnetochron C33N for the lower layers. However, a slight age inconsistency between the biostratigraphic correlation and the detrital zircon maximum depositional age may imply that the fossils are reworked. Regardless, these new data allow us to correlate the strata at Cape Marsh to the Santa Marta and Rabot formations (or possibly the lower part of the Snow Hill Island Formation) in the northern part of the James Ross Basin