On the function of the floccular complex of the vertebrate cerebellum: implications in paleoneuroanatomy

The cerebellum floccular complex lobes (FCLs) are housed in the FCL fossa of the periotic complex. There is experimental evidence indicating that the FCLs integrate visual and vestibular information, responsible for the vestibulo-ocular reflex, vestibulo-collic reflex, smooth pursuit and gaze holding. Thus, the behavior of extinct animals has been correlated with FCLs dimension in multiple paleoneuroanatomy studies. Here I analyzed braincase endocasts of a representative sample of Mammalia (48 species) and Aves (59 species) rendered using tomography and image segmentation and tested statistical correlations between the floccular complex volume, ecological and behavioral traits to assess various previously formulated paleobiological speculations. My results demonstrate: 1) there is no significant correlation between relative FCL volume and body mass; 2) there is no significant correlation between relative FCL and optic lobes size in birds; 3) average relative FCL size is larger in diurnal than in nocturnal birds but there is no statistically significant difference in mammals; 4) feeding strategies are related with different FCL size patterns in birds, but not in mammals; 5) locomotion type is not related with relative FCL size in mammals; 6) agility is not significantly correlated with FCL size in mammals. I conclude that, despite the apparent relation between FCL size and ecology in birds, the cerebellum of tetrapods is a highly plastic structure and may be adapted to control different functions across different taxonomic levels. For example, the european mole (Talpa europaea) which is fossorial and practically blind, has a FCL fossae relative size larger than those of bats, which are highly maneuverable. Therefore, variation in FCL size may be better explained by a combination of multiple factors with relation to anatomical and phylogenetic evolutionary constraints

Evaluation of Lateral Cephalometric Variables and Its Efficacy in Identification of Sexual Dimorphism in Chennai Population using Discriminant Function Analysis

AIM OF THE STUDY: To evaluate the lateral cephalometric variables and its efficacy in identification of sexual dimorphism in Chennai population using discriminant function analysis. MATERIAL AND METHODS: A total of 100 lateral cephalographs were collected of 50 males and 50 females belonging to Chennai population. The cephalometric variables were evaluated to arrive at a discriminant function equation which was further assessed for its realibility among the study subjects. The variables used were Ba-ANS, N-ANS, Ba-N, N-M, Fs-Ht, Ma-FH, Ma-Ht, Ma-Wd to arrive at a discriminant function equation for identification of sex. RESULTS: All the nine cephalometric variables were found to be highly significant with a p-value of less than 0.001. Among the 9 variables Fs-Ht, Ba-ANS, MA-Ht, Ma-Wd, N-ANS, Ba-N were found to be highly discriminative in sex determination. The discriminant function equation derived was cross validated within the study subjects were an overall accuracy of 95% was obtained. It was found to have an accuracy of 98% in males and 92% in females. CONCLUSION: This study concluded that among the nine cephalometric variables Fs-ht, Ba-ANS, MA-ht, Ma-wd, N-ANS, Ba-N were found to be highly discriminative in sex determination. The derived discriminant function equation could be a valuable tool in future forensic investigation in Chennai population