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The ability to identify the sex of animals accurately is important in population studies. Emydid turtles (Testudines: Emydidae) demonstrate a number of sexually dimorphic characters, including head (cranial) size and structure. Field observations from a long-term study of midland painted turtles ( Chrysemys picta marginata) in Algonquin Provincial Park, Ontario, Canada, suggested distinct differences in external head morphology between the sexes. We evaluated these putative sexual differences in C. picta head morphology by conducting a visual questionnaire involving human observers of varying levels of experience (novice, beginner, intermediate, and advanced). Observers were capable of distinguishing the sexes based solely on head morphology with a high degree of accuracy (between 79% and 86% success) across experience levels. Observers identified head shape as a defining character distinguishing the sexes. We suggest that visual questionnaires are a quantifiable method of assessing dimorphic characters that can be used in addition to traditional morphometrics or geometric morphometrics to demonstrate a visual, rather than simply statistical, difference among characters and sexes. Despite the breadth of research conducted on C. picta, our study is among the first to describe, assess, and discuss the functional significance of head dimorphism in this model species. [ABSTRACT FROM AUTHOR]

Kyphosis, a congenital humpback condition of the spinal column, has been reported across a broad range of chelonian taxa. These reports are often of single observations and lack background information about the history of the animal(s) involved. A kyphotic female midland painted turtle ( Chrysemys picta marginata) reported herein is a member of a long-term mark-recapture study in Algonquin Park (Ontario, Canada), providing a unique opportunity to document life-history characters of a kyphotic turtle over 18 yrs and draw comparisons to other members of her cohort and population. Despite her spinal deformity, the somatic growth, body size, age at sexual maturity, and reproduction of the kyphotic female have been similar to those of nonkyphotic females in our long-term study population, suggesting that the condition has not compromised her fitness. [ABSTRACT FROM AUTHOR]