Data from: A new hybodont shark (Chondrichthyes: Elasmobranchii) from the Upper Triassic Tiki Formation of India with remarks on its dental histology and biostratigraphy

A new lonchidiid genus Pristrisodus from the Upper Triassic Tiki Formation of India is described based on multiple, well-preserved, isolated teeth. Comparative analysis resulted in synonymizing Parvodus tikiensis and Lissodus duffini, which are known from the same horizon and resulted in a new taxon, Pristrisodus tikiensis. These teeth are elongated with mesiodistal length greater than or equal to twice the labiolingual width, and have a high principal cusp, lateral cusplets, a distinct ridge near the crown-root junction labially and higher up on the crown lingually, weak ornamentation, linear depression along the crown-root junction. Five morphotypes based on overall shape, robustness and crown height are determined. The teeth show a gradual monognathic heterodonty. The anterolateral teeth (morphotypes I−II) have high, pyramidal principal cusp with 2-3 small but pointed cusplets, and triangular labial and lingual protuberance, and the posterolateral teeth (morphotypes III−IV) have four incipient cusplets, relatively low principal cusp, bilobed/rounded hanging labial and incipient lingual protuberances. Morphotype V comprises anterior teeth as these are broad, triangular and robust, and have rounded/blunt principal cusp, one cusplet, and low, hanging labial peg. Multivariate analyses corroborate the qualitative assessment of the Indian hybodonts. Dental histology of Pristrisodus shows that it is distinctly different from other lonchidiid genera. The assemblage of freshwater sharks along with other vertebrate microfossils of the Tiki Formation shows similarity with that of the Lower Tecovas Formation of the Chinle Group, USA. The euryhaline nature has resulted in the adaptation of the hybodonts to freshwater systems in India during the Carnian.基于多枚保存完好的孤立牙齿，本文记述了产自印度上三叠统提基组（Tiki Formation）的隆齿鲨科（Lonchidiidae）一新属Pristrisodus。经比较解剖学分析，将产自同一地层位的Parvodus tikiensis与Lissodus duffini归为同物异名，并建立新分类单元Pristrisodus tikiensis。该属牙齿呈长条形，近中远中长度不小于唇舌径宽度的两倍；具高主齿尖、侧小齿尖，唇侧冠根交界附近及舌侧冠部上方具明显脊状结构，纹饰较弱，冠根交界处具线状凹陷。根据整体形态、粗壮程度及冠高，可将该属牙齿划分为5种形态型。该属牙齿呈现出渐进式单颌异齿型特征：前侧位牙齿（形态型I~II）具高而呈锥状的主齿尖，带有2~3枚细小尖锐的侧小齿尖，唇侧与舌侧均具三角形隆起；后侧位牙齿（形态型III~IV）具4枚雏形小齿尖，主齿尖相对低矮，唇侧隆起呈悬垂状双叶/圆形，舌侧隆起为雏形。形态型V为前位牙齿，其形态宽扁呈三角形且较为粗壮，主齿尖圆润/钝圆，带有1枚小齿尖，唇侧具低矮悬垂状齿突。多变量分析验证了印度弓鲛类（Hybodontiformes）的定性形态学评估结果。Pristrisodus的牙齿组织学特征表明，其与其他隆齿鲨科属类存在显著差异。提基组中淡水鲨类与其他脊椎动物微化石的组合特征，与美国钦勒群（Chinle Group）下特科瓦组（Lower Tecovas Formation）的化石组合特征相似。在卡尼期（Carnian），广盐性（euryhaline）特征使得弓鲛类能够适应印度的淡水环境。