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Transactions of the Illinois State Academy of Science [Volume 116 (2023)]

Population Characteristics of the Lesser Siren (Siren intermedia) in Central Illinois

Author: Baylee Thornton

The Lesser Siren (Siren intermedia) is a fully aquatic salamander found throughout the central and south-central United States. The Illinois Department of Natural Resources identifies the Lesser Siren as a Species in Greatest Conservation Need, but there is minimal published information available on Illinois populations. Knowledge gaps about a species create misconceptions about population viability, resulting in insufficient conservation efforts or efforts that do not reflect the current population status. Over a 7-month trapping period in 2020, mark-recapture data were gathered on characteristics of a single population of Lesser Siren occupying a ditch network in Central Illinois to help fill information gaps on this species and to compare with other population studies throughout its range. The estimated population size was 132 Siren (95% CI of 49 – 485) at a density of 0.26 Siren per linear meter. Individuals ranged from 281-360 mm in total length, with mean total length of 322.3 mm and mean snout-vent length of 216.61 mm. Adult males were significantly larger than adult females in total length, snout-vent length, and wet mass. While individual sizes and estimated population size were similar to those observed in other studies conducted in Arkansas and Missouri, density was lower than reported in these studies, as well as studies conducted in Texas. This is the first study on population characteristics of Lesser Siren in Illinois and provides meaningful data for filling information gaps and understanding the species’ viability in the state.

Correlations Between Cranial Angles and Classification of Malocclusion in Anatomically Modern Homo sapiens

Authors: Emily Bone and Miranda Karban

Dental malocclusion describes incorrect alignment of the maxillary and mandibular first molars. This causes irregular bite alignment and can result in other physiological issues related to the jaw or mouth. Many studies have been conducted to look for correlations between various craniofacial angles and classification of malocclusion. However, most of these studies focused on differences between classes without comparing these differences between multiple age groups. This study investigates correlations between the cranial base angle, maxillary protrusion angle (SNA), mandibular protrusion angle (SNB) and classification of malocclusion, as well as sexual dimorphism and developmental variations of those angles. Measurements were collected from a longitudinal sample of anatomically modern human cranial radiographs, ranging in age from 5.0 to 16.2 years. Results showed a significant difference in mandibular protrusion between the youngest and oldest sampled age groups, significant difference in maxillary protrusion between males and females at the youngest sampled age group, and significant differences in the mandibular protrusion angle between each of the three classes of malocclusion. These findings can help to further our understanding of the relationship between craniofacial development and the classification of malocclusion.