More than one large constrictor snake lurked around paleolake Messel

The largest terrestrial snakes from Europe pertain to the constrictor genus Palaeopython ROCHEBRUNE, 1880. Two specimens from the early-middle Eocene of Messel, Germany, are the first skeletons referable to Palaeopython, which we describe as Palaeopython schaali sp. nov. The new species shares numerous derived features with Messelopython freyi ZAHER & SMITH, 2020, including a sigmoidal lateral margin of the maxilla, a highly distinctive ectopterygoid-pterygoid articulation, a crescentic supra-orbital element, and a strongly convex prearticular crest of the compound bone. We erect the family Messelopythonidae nov for the fossil genera Palaeopython and Messelopython. P. schaali has a highly unique posterodorsal circumorbital element that in its great extent is similar to the combined supra-and post-orbital elements ofM. freyi. P. schaali co-existed with the stem boid Eoconstrictor fischeri (SCHAAL, 2004), demonstrating that similarly sized species of these two lineages of hyper-macrostomate snakes were sympatric. Although evidence of body proportions suggests a terrestrial way of life for Messelopythonidae, several skull traits such as the sigmoid-shaped maxilla, highly enlarged anterior maxillary teeth, and a straight lower jaw suggest an arboreal lifestyle for P. schaali. Analysis of morphometric data provides no support for the presence of pit organs in this species.