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A new hapalodectid (Mesonychia, Mammalia) from the Late Paleocene of the Qianshan Basin (Anhui Province, China): new data on the radiation of the hapalodectids
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Mesonychians are an extinct group of primitive hoofed mammals. They have been found all over Laurasia and were well diversified: more than 20 genera are presently recorded. Mesonychia are divided into two families: Hapalodectidae and Mesonychidae. Hapalodectidae are recorded from the late Paleocene to the middle Eocene in Asia (Gashatan to Irdinmanhan), and in the early Eocene in North America (from Wasatchian to early Bridgerian). Hapalodectids remained small: the species of Hapalodectes, the type genus of the family, weighed between 500 g and 1 kg. Because the hapalodectids are relatively rare mammals, the discovery of new specimens, especially in the Paleocene, is crucial for understanding the evolution of these peculiar mammals. Field work in Qianshan Basin (Anhui Province, China) led to the discovery of a new lower jaw of the mesonychian Hapalodectes in Gashatan (late Paleocene) sediments. It is worth noting that the fragmentary mandible is only the third specimen of Hapalodectidae discovered in the Paleocene, and the first in southeast China. The premolars and molars of the new fossil are morphologically similar to Hapalodectes dux, the most primitive hapalodectid, but their relative proportions recall H. paleocenus and the Eocene Hapalodectes species. As a result, the fossil described herein appears to be different from the other previously described species of Hapalodectes in being morphologically intermediate between H. dux and the other Hapalodectes species; it is thus identified as a new species. Its discovery is important because it sheds light on the initial radiation of the hapalodectids. The presence of the most primitive hapalodectids in Mongolia (e.g., H. dux) suggests that the Mongolian area is the center of origination of this carnivorous family. The differences between the new species and the Eocene hapalodectids from China, H. huanghaiensis and H. hetangensis, imply that these species do not derive from the newly described species. Therefore, the new Chinese hapalodectid allows reconstructing the existence of two dispersals from the Mongolian area to the southeast of China, before and shortly after the Paleocene–Eocene boundary. At that latter time, Hapalodectes also dispersed from Asia to North America; this event was part of the 'East of Eden' dispersals. The Paleocene/Eocene transition thus appears as a crucial event for the distribution and radiation of the hapalodectids with the establishment of two distinct groups, respectively in North America and in the southeast of China. Grant Information This abstract is a contribution to the Belgian Bilateral Cooperation Project Belspo BL/36/C54 and China International S&T Cooperation Project MOST 2009DFA32210.
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RBINS Staff Publications 2016
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A new hero emerges: another exceptional mammalian spine and its potential adaptive significance
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RBINS Staff Publications
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A new inioid (Cetacea, Odontoceti, Delphinida) from the Miocene of Peru and the origin of modern dolphin and porpoise families
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RBINS Staff Publications 2017
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A new insight of the MIS 3 Dansgaard-Oeschger climate oscillations in western Europe from the study of a Belgium isotopically equilibrated speleothem.
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RBINS Staff Publications 2024
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A new jewel-like species of the pill-millipede genus Sphaerobelum Verhoeff, 1924 (Diplopoda, Sphaerotheriida, Zephroniidae) from Thailand
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RBINS Staff Publications 2023 OA
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A new Jurassic theropod from China documents a transitional step in the macrostructure of feathers
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RBINS Staff Publications 2017
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A new karst-dwelling, colorful pitviper (Viperidae: Trimeresurus) from northern Peninsular Thailand
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We describe a colorful and distinctively patterned, karst-dwelling pitviper, Trimeresurus kuiburi sp. nov., from the isolated, coastal massif of Khao Sam Roi Yot in Kui Buri District, Prachuap Khiri Khan Province, in northern Peninsular Thailand. The new species, member of the ‘Cryptelytrops group’ sensu Malhotra & Thorpe (2004) and morphologically and genetically allied to Trimeresurus kanburiensis and T. venustus, differs from all pitviper taxa by a combination of red/purple bands on a green dorsum; a white concave suborbital stripe in males (straight and less visible in females); white, spaced vertebral dots in males (absent in females); pale green belly lacking dark dots or stripe on the lateral sides of the ventrals; partially fused first supralabial and nasal scale; 19 dorsal scale rows at midbody; 164–171 ventrals; 63–65 subcaudals in males, 51–53 in females; maximal known SVL of 451 mm; and long, papillose hemipenes.
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RBINS Staff Publications 2021
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A new kentriodontine dolphin from the Middle Miocene of Portugal
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RBINS Staff Publications
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A new kogaionid multituberculate mammal from the Maastrichtian of the Transylvanian Basin, Romania
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Abstract: The Latest Cretaceous (Maastrichtian) terrestrial sedimentary sequences of the Hateg Basin in Transylvania are well known for the so-called “Hateg Island” vertebrate faunas, which evolved in endemic (insular?) conditions. In addition to frogs, lizards, turtles, crocodilians, birds and dinosaurs, peculiar multituberculate mammals have been recorded, all belonging to the family Kogaionidae. Here, a new species of the genus Barbatodon is reported from the Maastrichtian S¸ ard Formation in the Transylvanian Basin (Alba County, Romania). Barbatodon oardaensis n. sp. is characterized by M1 cusp formula 3:4:2 and is much smaller than the two other Maastrichtian kogaionids from Transylvania, Barbatodon transylvanicus and Kogaionon ungureanui. The origin and paleobiogeography of kogaionids are discussed. Résumé: Les séquences continentales du Crétacé terminal (Maastrichtien) du bassin de Hateg en Transylvanie sont réputées pour leurs faunes de vertébrés originaires de « l’île de Hateg », qui ont évolué dans des conditions endémiques (insulaires ?). Hormis des grenouilles, lézards, tortues, crocodiles, oiseaux et dinosaures, des mammifères multituberculés particuliers ont également été mentionnés, tous appartenant à la famille des Kogaionidae. Une nouvelle espèce du genre Barbatodon est décrite dans le Maastrichtien de la Formation de S¸ ard, dans le bassin de Transylvanie (district d’Alba, Roumanie). Barbatodon oardaensis n. sp. est caractérisée par une formule dentaire de M1 3:4:2 et est plus petite que les deux autres kogaionidés de Transylvanie, Barbatodon transylvanicus et Kogaionon ungureanui. L’origine et la paléobiogéographie des kogaionidés sont discutées.
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RBINS Staff Publications
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A New Large Hyainailourine from the Bartonian of Europe and Its Bearings on the Evolution and Ecology of Massive Hyaenodonts (Mammalia)
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We describe a new large-sized species of hypercarnivorous hyainailourine–Kerberos langebadreae gen. & sp. nov.–from the Bartonian (MP16) locality of Montespieu (Tarn, France). These specimens consist of a skull, two hemimandibles and several hind limb elements (fibula, astragalus, calcaneum, metatarsals, and phalanges). Size estimates suggest K. langebadreae may have weighed up to 140 kg, revealing this species as the largest carnivorous mammal in Europe at that time. Besides its very large size, K. langebadreae possesses an interesting combination of primitive and derived features. The distinctive skull morphology of K. langebadreae reflects a powerful bite force. The postcranial elements, which are rarely associated with hyainailourine specimens, indicate an animal capable of a plantigrade stance and adapted for terrestrial locomotion. We performed the first phylogenetic analysis of hyainailourines to determine the systematic position of K. langebadreae and to understand the evolution of the group that includes other massive carnivores. The analysis demonstrates that Hemipsalodon, a North American taxon, is a hyainailourine and is closely related to European Paroxyaena. Based on this analysis we hypothesize the biogeographic history of the Hyainailourinae. The group appeared in Africa with a first migration to Europe during the Bartonian that likely included the ancestors of Kerberos, Paroxyaena and Hemipsalodon, which further dispersed into North America at this time. We propose that the hyainailourines dispersed into Europe also during the Priabonian. These migrants have no ecological equivalent in Europe during these intervals and likely did not conflict with the endemic hyaenodont proviverrines. The discovery of K. langebadreae
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