Exploring ancestral phenotypes and evolutionary development of the mammalian middle ear based on Early Cretaceous Jehol mammals

We report a new Cretaceous multituberculate mammal with 3D auditory bones preserved. Along with other fossil and extant mammals, the unequivocal auditory bones display features potentially representing ancestral phenotypes of the mammalian middle ear. These phenotypes show that the ectotympanic and the malleus-incus complex changed notably during their retreating from the dentary at various evolutionary stages and suggest convergent evolution of some features to extant mammals. In contrast, the incudomalleolar joint was conservative in having a braced hinge configuration, which narrows the morphological gap between the quadroarticular jaw joint of non-mammalian cynodonts and the incudomalleolar articulations of extant mammals. The saddle-shaped and abutting malleus-incus complexes in therians and monotremes, respectively, could have evolved from the braced hinge joint independently. The evolutionary changes recorded in the Mesozoic mammals are largely consistent with the middle ear morphogenesis during the ontogeny of extant mammals, supporting the relation between evolution and development.     

Examiner scoring of ambiguous WISC-R responses

Fabricated test protocols were used to study how effectively examiners agree in scoring ambiguous WISC-R responses. Clinical and school psychologists (N = 62) and graduate students (N = 48) scored WISC-R Similarities, Comprehension, and Vocabulary responses obtained in a group administration procedure. From over 15,000 responses obtained, only unusual, atypical, or ambiguous responses were selected; 726 responses were scored, with 11 groups of 10 raters each scoring 66 responses. Considerable scoring disagreement occurred. Unanimous agreement (within each group of 10 raters) was found on only 13% of the responses, while 80% of the raters agreed on 44% of the responses. Rates of scoring agreement were not related to level of rater experience, but were related to specific subtests. Higher rates of agreement were found on the Similarities and Comprehension subtests than on the Vocabulary subtest for both experienced and inexperienced raters. The results suggest that even with the improved WISC-R manual, scoring remains a difficult and challenging task.