Pacarana

Abstract: Confirmation of the presence and new records of the pacarana (Rodentia: Dinomyidae: Dinomys branickii) in Colombia. The pacarana (Dinomys branickii) is a Neotropical rodent that inhabits forests of the Andes and Amazonian between 300 and 3200 m. We built a distribution model for the species in Colombian Andes using the software Maxent and selected 10 localities where we searched evidences of pacarana presence (footprints, scats, dens and foraging signs). We confirmed the pacarana presence in 4 localities of the Andes of Colombia. We added two new records of pacarana in Colombia. We extend the geographic distribution of pacaranas at least of 1500 m in the piedmonts of the Andes slopes and lowlands of the Choco Biogeografico of Colombia.

Abstract: The pacarana, Dinomys branickii, is the only living member of the family Dinomyidae. This caviomorph rodent is known only from western South America in the Andes mountains from Colombia to southeastern Peru and western Bolivia [4]. Cabrera identifies Amable Maria in the department of Junin in Peru as the type locality. Cabrera and Yepes [5], as well as Walker [25], list the Andes of Ecuador and Brazil as additional countries where pacaranas are found. Hodge [16] identifies the Chanchamayo region of Peru as the origin of a specimen he observed in Lima. Anthony [3] describes a large specimen from La Candela, Huila, Colombia. Lonnberg [17] describes four specimens, acquired near Gualea, Ecuador, at elevations of from 5,000 to 6,500 feet, on the eastern slopes of the Andes. Moojen [18], gives the Rio Pauini at the junction of the Purus river as a Brazilian location for pacarana.

Abstract: In this contribution we describe the fossil remains of a new genus and species of a giant rodent, Arazamys castiglionii (Mammalia, Rodentia, Dinomyidae), from Arazati beach in San Jose Department, southern Uruguay. The specimen was exhumed from pelitic sediments of the Camacho Formation, biostratigraphically assigned to the late Miocene Huayquerian South American Land Mammal Age. The remains include an incomplete skull (braincase, auditory region, and nearly full dentition) and the atlas. Based on comparative studies of the anatomy of the auditory region, we describe 2 morphologies for the subfamily Eumegamyinae, 1 characterized by a short meatus acusticus externus, a great development of the foramen stylomastoideum, and a conspicuous ectotympanic cavity, and a 2nd characterized by a long meatus acusticus externus and lack of the ectotympanic fossa. The potential taxonomic and systematic value of the auditory region in Dinomyidae is discussed.

Abstract: Introduction Among the great diversity of the order Rodentia, the “New World Hystricognathi”, or caviomorphs are a very characteristic group from the Neotropical region. This group, whose fossil record begins in the late Eocene (Antoine et al ., 2011), and is included in the infraorder Hystricognathi (Huchon and Douzery, 2001; Woods and Kilpatrick, 2005), comprises more than 50 genera in 13 families. One of the peculiarities of the extant caviomorphs is their wide range of size, between ∼200 g and ∼60 kg (Sanchez-Villagra et al ., 2003). The latter is the maximum body mass among extant rodents (Mones and Ojasti, 1986) and occurs in Hydrochoerus hydrochaeris (known colloquially as capybaras), considered the giant of the group. South America is also home of the pacarana, Dinomys branickii , a large, enigmatic caviomorph rodent that can be found in the rainforests of Brazil, Bolivia, Colombia, Ecuador and Peru (Figure 6.1). This is the only living member of the family Dinomyidae, which is notorious for its great past diversity (Frailey, 1986; Mones, 1986; Rinderknecht et al ., 2011). With a body mass that varies from 10 kg to 15 kg (White and Alberico, 1992), the pacarana is one of the biggest living rodents. However, dinomyid rodents used to be much larger. Many taxa from this family achieved extraordinary body sizes, especially those that belong to the extinct subfamily Eumegamyinae (Rinderknecht and Blanco, 2008). This subfamily contains the biggest rodents that ever existed (see Figures 6.2–6.4). Recorded since the middle Miocene (but see Krapovickas and Nasif, 2011), the diversity of the Dinomyidae has been repeatedly corroborated with a great number of findings. Nowadays, approximately 60 extinct species are known, all of them distributed within South America (Mones, 1986; Rinderknecht and Blanco, 2008; Rinderknecht et al ., 2011). In this chapter we summarize the principal aspects of the history, anatomy, systematics and taxonomy of these enigmatic rodents. All texts shown in square brackets and italics are translations from Spanish.