The Enantiornithes is the most speciose clade of Mesozoic avialans with over 60 named taxa reported from most continents that span the whole Cretaceous.Most of the fossil remains of this clade,as well as those of othe...The Enantiornithes is the most speciose clade of Mesozoic avialans with over 60 named taxa reported from most continents that span the whole Cretaceous.Most of the fossil remains of this clade,as well as those of other early diverging avialans are preserved in two-dimensions.This complicates efforts to extract detailed anatomical information from the skull,in which the composite elements are delicate and thus not easily observable through conventional methods.The scarcity of well-preserved early avialan skulls,as well as the limited number of specimens that have been analyzed using computed tomography scanning,consequently circumscribes a large morphological gap in the fossil record during the transition from the heavy and akinetic dinosaurian skull to the lightweight and kinetic bird skull.Here,we present a three-dimensional digital reconstruction of the skull and part of the cervical vertebrae of a new specimen of the enantiornithine Parabohaiornis martini from the Early Cretaceous of China.Our results demonstrate that Parabohaiornis retains the plesiomorphic non-avialan dinosaurian temporal and palatal configurations,reinforcing the recent hypothesis that the temporal and palatal regions are evolutionarily conservative and that the akinetic skull has been conserved well into diversification of early branching avialans.展开更多
The origin of birds from theropod dinosaurs,by any measures,is the most eye-catching evolutionary transition in the history of life,which encompasses numerous extensive morphological and biological changes.Compared to...The origin of birds from theropod dinosaurs,by any measures,is the most eye-catching evolutionary transition in the history of life,which encompasses numerous extensive morphological and biological changes.Compared to postcranium,little progress has been made regarding the evolutionary assemblage of the birds’skull,because of few detailed early records of cranial materials of stem lineages.Anchiornis is the oldest known record of the Paraves(~160 Ma),the most inclusive clade that contains all living birds but not Caudipteryx or Epidexipteryx.With hundreds of known specimens,Anchiornis constitutes an ideal taxon for investigating morphological modifications across the theropod-bird transition,but its cranial morphology remains enigmatic.Here we present in-depth description of the cranial morphology of Anchiornis based on three-dimensional reconstruction of a well-preserved specimen,including elements from the temporal and palatal regions that are poorly recognized previously.Our study shows that Anchiornis retains the plesiomorphic dinosaurian condition in having a diapsid akinetic skull.The mixture of cranial characters,shared with dromaeosaurids,troodontids,and stemward avialans,present in Anchiornis demonstrates the complex history of early avialan cranial evolution.展开更多
文摘The Enantiornithes is the most speciose clade of Mesozoic avialans with over 60 named taxa reported from most continents that span the whole Cretaceous.Most of the fossil remains of this clade,as well as those of other early diverging avialans are preserved in two-dimensions.This complicates efforts to extract detailed anatomical information from the skull,in which the composite elements are delicate and thus not easily observable through conventional methods.The scarcity of well-preserved early avialan skulls,as well as the limited number of specimens that have been analyzed using computed tomography scanning,consequently circumscribes a large morphological gap in the fossil record during the transition from the heavy and akinetic dinosaurian skull to the lightweight and kinetic bird skull.Here,we present a three-dimensional digital reconstruction of the skull and part of the cervical vertebrae of a new specimen of the enantiornithine Parabohaiornis martini from the Early Cretaceous of China.Our results demonstrate that Parabohaiornis retains the plesiomorphic non-avialan dinosaurian temporal and palatal configurations,reinforcing the recent hypothesis that the temporal and palatal regions are evolutionarily conservative and that the akinetic skull has been conserved well into diversification of early branching avialans.
文摘The origin of birds from theropod dinosaurs,by any measures,is the most eye-catching evolutionary transition in the history of life,which encompasses numerous extensive morphological and biological changes.Compared to postcranium,little progress has been made regarding the evolutionary assemblage of the birds’skull,because of few detailed early records of cranial materials of stem lineages.Anchiornis is the oldest known record of the Paraves(~160 Ma),the most inclusive clade that contains all living birds but not Caudipteryx or Epidexipteryx.With hundreds of known specimens,Anchiornis constitutes an ideal taxon for investigating morphological modifications across the theropod-bird transition,but its cranial morphology remains enigmatic.Here we present in-depth description of the cranial morphology of Anchiornis based on three-dimensional reconstruction of a well-preserved specimen,including elements from the temporal and palatal regions that are poorly recognized previously.Our study shows that Anchiornis retains the plesiomorphic dinosaurian condition in having a diapsid akinetic skull.The mixture of cranial characters,shared with dromaeosaurids,troodontids,and stemward avialans,present in Anchiornis demonstrates the complex history of early avialan cranial evolution.
