First evidence of poisonous shrews with an envenomation apparatus

Abstract

Herein, we report evidence of an envenomation apparatus (EA) in two different species of extinct "giant" shrews, Beremendia and an indeterminate soricine (Mammalia, Eulipotyphla, Soricidae), documented by very well preserved fossil specimens recovered from two Early Pleistocene cave deposits of the Sierra de Atapuerca in Burgos, Spain. The two soricine taxa from Atapuerca have evolved specialized teeth as EAs, which differ from those of recently reported mammals of the Paleocene age, being more similar to the ones described in the modern Solenodon. This discovery reveals the first instance of shrews possessing what appears to be an EA, an evolutionary adaptation that, in these species, was probably related to an increase in body mass and hunting of a larger-sized prey. The Atapuerca specimens would have a highly specialized EA, one of the very few reported for an extinct or living mammal of any time. In addition to the presence of a gutter-like groove along the medial side of the crown of the lower incisors, these two species also present stout jaws and a modified mandibular symphysis with a conspicuous cavity, which in life would likely contain large amounts of connective tissue. The strong mandible architecture of these large shrews would be, in this way, reinforced by a more immovable symphysis, increasing the bite force exerted over a potential prey. This adaptation, together with the grooved incisors, would ensure a rapid and efficient transmission of the poisonous saliva to paralyze relatively large-sized prey.

The Snake with the Scorpion’s Sting: Novel Three-Finger Toxin Sodium Channel Activators from the Venom of the Long-Glanded Blue Coral Snake (Calliophis bivirgatus)

“…While a venom delivering wound can be created by any form of tooth capable of penetrating skin, in the advanced snakes enlarged rear teeth have independently evolved on multiple occasions and also display extensive variation [44], in some cases accompanied by grooving that is convergent with that seen in other extant and extinct venomous lineages including archosauriforms [66], conodonts [67], sphenodons [68], insectivorous mammals such as shrews and solenodons [69,70,71,72], and bird-like dinosaurs hypothesised to specialise in feeding upon on early birds [73]. …”

X Conferencias y Seminarios del Doctorado en Geología

“…Se trata de Dolinasorex glyphodon, endémica del yacimiento de Gran Dolina (Rofes y Cuenca-Bescós, 2009a), y Beremendia fissidens, presente en el de Sima del Elefante, ambos yacimientos de las cuevas de la Sierra de Atapuerca estando B. fissidens presente también, desde el Plioceno, en otros yacimientos de Eurasia (Rofes y Cuenca-Bescós, 2009b). Ambas se caracterizan por tener las cúspides de los dientes de color rojo debido a la presencia de óxidos o hidróxidos de hierro en el esmalte, carácter que comparten con el resto de musarañas de dientes rojos (Moya-Costa et al, 2017), por tener los incisivos inferiores acanalados, posiblemente adaptados a la inyección de veneno (Cuenca-Bescós y Rofes, 2007), tener la articulación temporomandibular dividida y con dos orientaciones diferentes y una sínfisis móvil (Furió et al, 2010).…”

Mammals

“…11 These animals have short, dense fur and a long, slender snout. Fossil records of the extinct giant shrews from the Early Pleistocene era indicate that these mammals had a rudimentary envenomation apparatus, probably as a means to increase body mass and hunt larger -sized prey.…”