Data from: An ecomorphospace for the Ammonoidea

The fossil conchs of ammonoids provide valuable information about the life habits of this extinct group. A new conch measurement, the apertural surface area, is introduced here along with modelled sizes of the buccal mass and the hyponome, based on ratios of these organs in comparison with the aperture height from the Recent Nautilus pompilius. A principal components analysis was performed using the three main characters (1) apertural surface area index (i.e., the ratio of the apertural surface and the conch diameter), (2) buccal mass area index (i.e., the ratio between the buccal mass area and the apertural surface area) and (3) coiling rate of the conch and reveals an ecomorphospace where life history traits can be tentatively assigned to species of the Ammonoidea. In this morphospace, Recent Nautilus has a marginal position, being one of the ectocochleate cephalopods with best properties for active life (capacity for handling large food items, rather good mobility). In contrast, most ammonoids possessed, at comparable conch sizes, much smaller buccal apparatuses and hyponomes, suggesting a more passive life history with reduced mobility potential and reduced capacities for larger prey items.菊石亚纲（Ammonoidea）的化石壳体，可为解析这一已灭绝类群的生活习性提供关键信息。本研究引入一项全新的壳体测量指标——口面面积，并基于现生珍珠鹦鹉螺（Nautilus pompilius）的口部高度与上述两类器官的比例关系，推导出了口球与漏斗的模拟尺寸。 本研究选取三项核心性状开展主成分分析：1. 口面面积指数（即口面面积与壳体直径的比值）；2. 口球面积指数（即口球面积与口面面积的比值）；3. 壳体旋卷速率。分析结果揭示出一处生态形态空间，可据此将生活史性状暂定归属至菊石亚纲各物种。 在该生态形态空间中，现生鹦鹉螺处于边缘位置，是适配主动生活的外壳头足类（ectocochleate cephalopods）代表类群之一，具备处理大型食物的能力与较为优异的运动性能。与之相反，在壳体尺寸相当的前提下，绝大多数菊石拥有的口器与漏斗尺寸均显著更小，这暗示其生活史更为被动，运动潜力受限，且捕食大型猎物的能力偏弱。