Background: Bone fracture frequencies and survival rates are essential parameters in skeleton evolution, but information on the functional consequences of naturally healed fractures is scarce. No leg bone fracture hea...Background: Bone fracture frequencies and survival rates are essential parameters in skeleton evolution, but information on the functional consequences of naturally healed fractures is scarce. No leg bone fracture healing in the wild has been reported so far from long-legged Charadriiformes(waders), which depend on bipedal locomotion for feeding.Methods: We documented a healed but malaligned tarsometatarsus fracture in a wild Willet(Tringa [Catoptrophorus]semipalmata), and a malaligned tibiotarsus fracture in a Curlew(Numenius arquata) skeleton from a museum collection. Functional consequences of the malalignments were evaluated by kinematic analyses of videos(Willet) and in silico 3D modeling(Curlew).Results: The Willet's left tarsometatarsus exhibited an angular malalignment of 70°, resulting in a limping gait that was less pronounced at high than at low walking speed. The bird seemed unable to club the toes of the left foot together, apparently a secondary effect of the deformity. The Curlew's tibiotarsus showed an angular and an axial malalignment, causing the foot to rotate outwards when the intertarsal joint was flexed. Despite the severe effects of their injuries, the birds had survived at least long enough for the fractures to heal completely.Conclusions: Somewhat unexpectedly, leg fractures are not necessarily fatal in long-legged waders, even if deformities occur in the healing process. Bipedal locomotion on vegetated grounds must have been impeded due to the bone malalignments in both analyzed cases. The birds probably alleviated the impact of their handicaps by shifting a larger proportion of their activities to vegetation-free habitats.展开更多
Knowledge of the higher-level phylogenetic relationships of birds has grown substantially during the past two decades due to the application of genomic data.However,the nomenclature of higher-level taxa has not become...Knowledge of the higher-level phylogenetic relationships of birds has grown substantially during the past two decades due to the application of genomic data.However,the nomenclature of higher-level taxa has not become more stable,due to the lack of regulation of taxon names above the level of superfamily by the ICZN,and the usage of rank-based nomenclature,which is not tied to clades in a phylogeny.Lack of regulation and the instability of rank-based nomenclature impede effective communication among systematists.We review support for higher-level avian clades using a set of 10 phylogenomic data sets,and identify clades that are supported by congruency of at least four of these.We provide formal definitions of the names of these clades based on the rules of the recently published PhyloCode.The names of 25 clades are here defined using minimum-crown-clade(n=23),minimum-clade(n=1)and maximum-crown-clade(n=1)definitions.Five new names are introduced here:Dinocrypturi,Pteroclimesites,Musophagotides,Phaethoquornithes and Pelecanes.We also review diagnostic apomorphies of the relevant clades,and identify known synonyms and homonyms.By establishing a formal link between higher-level taxon names and well-supported phylogenetic hypotheses,our phylogenetic definitions will provide a solid basis for the stabilization of avian higher-level nomenclature.展开更多
文摘Background: Bone fracture frequencies and survival rates are essential parameters in skeleton evolution, but information on the functional consequences of naturally healed fractures is scarce. No leg bone fracture healing in the wild has been reported so far from long-legged Charadriiformes(waders), which depend on bipedal locomotion for feeding.Methods: We documented a healed but malaligned tarsometatarsus fracture in a wild Willet(Tringa [Catoptrophorus]semipalmata), and a malaligned tibiotarsus fracture in a Curlew(Numenius arquata) skeleton from a museum collection. Functional consequences of the malalignments were evaluated by kinematic analyses of videos(Willet) and in silico 3D modeling(Curlew).Results: The Willet's left tarsometatarsus exhibited an angular malalignment of 70°, resulting in a limping gait that was less pronounced at high than at low walking speed. The bird seemed unable to club the toes of the left foot together, apparently a secondary effect of the deformity. The Curlew's tibiotarsus showed an angular and an axial malalignment, causing the foot to rotate outwards when the intertarsal joint was flexed. Despite the severe effects of their injuries, the birds had survived at least long enough for the fractures to heal completely.Conclusions: Somewhat unexpectedly, leg fractures are not necessarily fatal in long-legged waders, even if deformities occur in the healing process. Bipedal locomotion on vegetated grounds must have been impeded due to the bone malalignments in both analyzed cases. The birds probably alleviated the impact of their handicaps by shifting a larger proportion of their activities to vegetation-free habitats.
文摘Knowledge of the higher-level phylogenetic relationships of birds has grown substantially during the past two decades due to the application of genomic data.However,the nomenclature of higher-level taxa has not become more stable,due to the lack of regulation of taxon names above the level of superfamily by the ICZN,and the usage of rank-based nomenclature,which is not tied to clades in a phylogeny.Lack of regulation and the instability of rank-based nomenclature impede effective communication among systematists.We review support for higher-level avian clades using a set of 10 phylogenomic data sets,and identify clades that are supported by congruency of at least four of these.We provide formal definitions of the names of these clades based on the rules of the recently published PhyloCode.The names of 25 clades are here defined using minimum-crown-clade(n=23),minimum-clade(n=1)and maximum-crown-clade(n=1)definitions.Five new names are introduced here:Dinocrypturi,Pteroclimesites,Musophagotides,Phaethoquornithes and Pelecanes.We also review diagnostic apomorphies of the relevant clades,and identify known synonyms and homonyms.By establishing a formal link between higher-level taxon names and well-supported phylogenetic hypotheses,our phylogenetic definitions will provide a solid basis for the stabilization of avian higher-level nomenclature.
