Indarctos

Abella, Juan, Hontecillas, Daniel, Valenciano, Alberto, Montoya, Plinio, Morales, Jorge, Pesquero, María Dolores & Alcalá, Luis, 2019, The last record of an ailuropod bear from the Iberian Peninsula, Geodiversitas 41 (23), pp. 797-809 : 800

THE GENUS INDARCTOS IN THE FOSSIL RECORD

The genus Indarctos comprises medium to large-sized bears from the late Miocene, with an omnivorous diet ( Montoya et al. 2001; Viranta 2004; Abella 2011; Abella et al. 2013; Monescillo et al. 2014; Domingo et al. 2016). Although comprehensively studied, there is not a full consensus about their phylogenetic relationships. Some authors ( Hendey 1972; Qiu et al. 2014) relate them to the genus Agriotherium (considered a Hemicyonidae by the authors of the present paper) and others consider it to be a basal Ursidae ( Abella et al. 2012, 2014). However, the most recent phylogenetic analyses, based on cranial, mandibular and dental characters, include Indarctos spp. in the Ailuropodinae ( Abella et al. 2012; Qiu et al. 2014). This genus was indeed the predominant bear taxon during most of the late Miocene in the Northern Hemisphere ( Abella et al. 2014).

The first specimen currently referred to the genus Indarctos consists of a left mandible fragment from the Greek locality of Pikermi identified as Hyaenarctos sp. by Dames (1883), with Weithofer (1888) later referring it to H. atticus. However, in 1884 Lydekker created the species H. punjabiensis based on a broken maxilla (which included P4-M1) from the Siwaliks in India. In that paper he also assigned a maxilla with P4-M2 and a skull with Upper canine and P4-M2 from other localities to the same genus. The latter specimen has been the cause of most of the later taxonomic confusion in comparisons among species since this skull clearly can be assigned to the genus Agriotherium , due to the lack of a clear talon and different relative development of the main cusps in the M2.

Pilgrim (1913) moved some of these remains from the junior synonym genus Hyaenarctos (also later synonym of Agriotherium ) to the newly created genus Indarctos based on a maxillary fragment with M2 and broken M1 from the Siwa- liks. However, it was not until a year later ( Pilgrim 1913) that he measured, figured and compared this specimen to other, similar fossils, describing Indarctos salmontanus as the type species of the genus ( Pilgrim, 1914). Later Baryshnikov (2002) accepted only two species of the genus Indarctos , literally he stated: “The genus Indarctos comprises two species. I. arctoides ( Depéret, 1895) was found in Europe, northern Africa and Turkey, dating as the Vallesian (MN 9-11). I. punjabiensis ( Lydekker, 1884) known from the Turolian (MN 10-13) had a Holarctic range, occurring in Europe, northern Africa, in the central, southern and eastern parts of Asia, and in North America”. Therefore, although indirectly, he synonymized Pilgrim’s type species with Indarctos punjabiensis .

The oldest record of Indarctos comprises some specimens from MN 9 in the Vallesian basin of Vallès-Penedès, at the localities of Can Porull ( Villalta & Crusafont 1943, 1948) and later from Can Llobateres ( Crusafont & Kurtén 1976). These remains were assigned to Indarctos vireti Villalta & Crusafont, 1943 , a small sized member of the genus, with elongated molars, more primitive (less reduced) premolars, and well-developed diastemas between them.

Indarctos arctoides ( Depéret, 1895) , is documented from MN10. This species was first described from the French locality of Montredon, and can be found along the northern edge of the Mediterranean Sea, including Spain, France and Turkey ( Tobien 1955; Geraads et al. 2005; Abella 2011; Abella et al. 2014).

Finally, Indarctos punjabiensis (incl. I. atticus) has an extensive record in the Iberian Peninsula from MN10 to MN12. Most of these specimens were studied in detail by Montoya et al. (2001). Following the arguments of that paper we accept three species of Indarctos ; four, if we take include the peculiar I. anthracites (Weithofer, 1889), which is thought to be an insular form and is only represented by a single published specimen. These are I. vireti , I. arctoides and I. punjabiensis with the last species having the temporal range. The present study increases the stratigraphic range of the genus Indarctos in the Iberian Peninsula to the lower part of MN13.