Netherlands Journal of Geosciences — Geologie en Mijnbouw | 92 – 1 | 3-10 | 2013 Two rare mosasaurs from the Maastrichtian of Angola and the Netherlands A.S. Schulp1,2,*, M.J. Polcyn3, O. Mateus4,5 & L.L. Jacobs3 1 Natuurhistorisch Museum Maastricht, De Bosquetplein 6-7, 6211 KJ Maastricht, the Netherlands 2 Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, the Netherlands 3 Huffington Department of Earth Sciences, Southern Methodist University, Dallas, TX75275, USA 4 CICEGe, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Monte de Caparica, Portugal 5 Museu da Lourinhã, Rua João Luis de Moura 95, 2530-158 Lourinhã, Portugal * Corresponding author. Email: [email protected] Manuscript received: October 2011, accepted: June 2012 Abstract We report here the addition of two rare mosasaur taxa to the Maastrichtian marine amniote fauna of Angola, both of which are also found in northern Europe. The new specimens include a dentary fragment referable to the large carnivore Prognathodon cf. saturator and an isolated tooth of the small durophage Carinodens belgicus. Both were recovered from Maastrichtian outcrops in southern Angola in 2011. Additionally, a complete posterior mandibular unit of a large mosasaur from the type Maastrichtian of the Netherlands, collected some time prior to 1879 and previously identified as ‘Mosasaurus giganteus’, is described and reassigned here to Prognathodon saturator; historical issues surrounding the taxonomic attribution of this specimen are clarified. The new material extends the known geographic distribution of Prognathodon saturator and Carinodens belgicus. Keywords: Mosasauridae, Prognathodon, Carinodens, Maastrichtian, Angola, the Netherlands Introduction Limburg Province, the Netherlands); the holotype is now housed in the collections of the Natuurhistorisch Museum In recent years our knowledge of the marine reptile fauna of Maastricht (NHMM1998-141). This large globidensine mosasaur Angola has been greatly expanded through the efforts of the was a contemporary of the better known Mosasaurus hoffmanni PaleoAngola Project (Jacobs et al., 2006, 2009; Schulp et al., 2006, Mantell, 1829 and Plioplatecarpus marshi Dollo, 1882 (e.g. 2008; Mateus et al., 2009, 2011; Polcyn et al., 2010; Mateus et Kuypers et al., 1998; Mulder, 2003), but evidenced by the al., 2012). A number of new taxa have been reported (Schulp et extremely massive and robust skull and dentition, was clearly al., 2008; Mateus et al., 2009, 2011) and skeletal remains of other exploiting a separate and unique feeding niche. taxa previously known only from teeth have been described In this contribution, we report two new occurrences of P. (Polcyn et al., 2010). During the 2011 field season of the saturator; a short fragment of a dentary recovered by the PaleoAngola Project, remains of two rare mosasaur taxa were authors from the Maastrichtian of southern Angola in 2011 and recovered; the extremely large and robust mega-carnivore a well-preserved posterior mandibular unit (PMU) collected Prognathodon cf. saturator, and the diminutive durophagous from the type Maastrichtian of the Netherlands sometime prior Carinodens belgicus. to 1879. The latter is currently housed in the collections of the Prognathodon saturator Dortangs et al. 2002 was heretofore Institut Royal des Sciences Naturelles de Belgique, Brussels, known only from the holotype material recovered from the type Belgium. Maastrichtian (~66.1 Ma) of the St Pietersberg (near Maastricht, 3 Netherlands Journal of Geosciences — Geologie en Mijnbouw 92 – 1 | 2013 Carinodens belgicus Woodward 1891 (see also Dollo, 1913 and Bentiaba site (e.g. Schulp et al., 2008; Polcyn et al., 2010; Mateus Thurmond, 1969) is known primarily from isolated teeth from et al., 2012). the Maastrichtian type area of the Netherlands and Belgium (Schulp et al., 2004) and is also known from both shed teeth and Description relatively complete dentaries from Morocco, and more complete The specimen is severely weathered, and is composed of portions cranial and postcranial material from Jordan (Mustafa & of the right dentary. It preserves two complete alveoli, multiple Zalmout, 2001; Bardet et al., 2005, 2008; Kaddumi, 2009; Schulp isolated bone fragments, a single tooth crown and a few tooth et al., 2010). The species is known from the Maastrichtian fragments. The teeth are ankylosed to the dentary by a broad South Atlantic of Brazil (Price, 1957) and from the Congo basin tooth base elevated above the dorsal margin of the dentary. (Polcyn et al., 2010). Here we report the first occurrence from The single preserved tooth crown is robust, and measures the African Southern Atlantic. 68 mm tall. It is missing the enamel, but allows description of diagnostic features. The tooth is bicarinate and only very Institutional abbreviations slightly recurved posteriorly. There is no medial curvature. The tooth is constricted at the base and shows the swelling just IRScNB: Institut Royal des Sciences Naturelles de Belgique, above the base that is characteristic of Prognathodon (Bell, Brussels, Belgium; NHMM: Natuurhistorisch Museum Maastricht, 1997; Bardet et al., 2000; Schulp, 2006). Maastricht, the Netherlands; MGUAN-PA: Geological Museum, This combination of characters allows referral to the genus Universidade Agostinho Neto, Luanda, Angola (PaleoAngola Prognathodon and other closely related forms. Although the collection); MNHN: Muséum National d’Histoire Naturelle, outer layer of enamel is exfoliated from the dentine, the Paris, France; OCP: Office Chérifien des Phosphates, Khouribga, remaining surface is smooth and shows no signs of fluting or Morocco; TM: Teylers Museum, Haarlem, the Netherlands. other ornamentation, ruling out P. overtoni and P. solvayi in which the teeth possess these features. Smooth surfaces are Systematic palaeontology known in Prognathodon (Dollosaurus) lutugini, P. stadtmani, P. waiparaensis, P. kianda and the species previously referred – Order Squamata Oppel, 1811 to the genus Liodon (see Schulp, 2006 and Schulp et al., 2008). – Superfamily Mosasauroidea Gervais, 1853 (nom. transl. Camp, The robust nature of the specimen and the nearly circular 1923) cross-section of the teeth rules out Prognathodon kianda and – Family Mosasauridae Gervais, 1853 other Prognathodon species that have previously been referred – Subfamily Mosasaurinae Gervais, 1853 (nom. transl. Williston, to the genus Liodon (Schulp et al, 2008), in which the teeth are 1897) more laterally compressed. P. currii and Igdamanosaurus are – Tribe Globidensini Russell, 1967 (sensu Bell, 1997) ruled out on the basis of their domed appearance. Additionally, – Prognathodon Dollo, 1889 P. currii teeth are not elevated on a bony base of attachment. – Prognathodon saturator Dortangs et al., 2002 The specimen described herein has tooth crowns elevated above the bony margin of the jaw by the bony base of attachment as Holotype: NHMM1998-141 in P. giganteus, P. (Dollosaurus) lutugini (Lindgren, 2005), P. saturator, and P. overtoni (Lindgren 2005). P. overtoni was ruled Referred specimen out on the basis of possession of fluted surfaces. Morphologically, MGUAN-PA 169 (Fig. 1A-C) is a jaw fragment with one preserved the specimen described here is similar to P. (Dollosaurus) lutugini tooth. (Lindgren, 2005) which comes from the Lower Campanian of Sweden and the upper Campanian of the Ukraine (Lindgren, Locality and Horizon 2005), Prognathodon saturator from the Maastrichtian of the The specimen comes from the Tzimbio locality (initially reported Netherlands (Dortangs et al., 2002), and Prognathodon giganteus as the ‘Bentiaba 2’-locality in Mateus et al., 2012), some 15 km NE from the Upper Campanian of France (Bardet et al., 1997; Jagt, of the richly fossiliferous locality of Bentiaba, Namibe Province, 2005). Dollosaurus, however, is a much smaller species. P. Angola (Jacobs et al., 2006). This site exposes strata from the giganteus and P. saturator are similar in size, and although Maastrichtian Mocuio Formation. Inoceramid shell fragments Dortangs et al. (2002) provided character justification for characteristically present in the lower part of the section at separation of P. saturator from P. giganteus, those characters nearby Bentiaba are absent in the higher part of the section at are not preserved in the specimen described here. Additionally, both Bentiaba and Tzimbio. Inoceramids became extinct in the a range extension of either of those species cannot be mid Maastrichtian (MacLeod, 1996), suggesting this part of the conclusively ruled out. Nonetheless, the specimen described section (and the fossils therein) fall within the upper part of herein is most similar in size, morphology, and age to P. the Maastrichtian and thus MGUAN-PA 169 is part of a slightly saturator (which is also Maastrichtian in age) and we therefore younger fauna than the material described so far from the tentatively refer the new material to that species. 4 Netherlands Journal of Geosciences — Geologie en Mijnbouw 92 – 1 | 2013 Fig. 1. Prognathodon cf. saturator Dortangs et al., 2002, right dentary fragment MGUAN-PA-169, in medial view (A), tooth crown in occlusal (B) and lateral (C) views; Carinodens belgicus (Woodward, 1891), isolated tooth crown MGUAN-PA-171, in buccal (D), lingual (E), occlusal (F), basal (G) and posterior (H) views. Scale bars equal 1 cm. Referred specimen P. saturator (Dortangs et al., 2002; Schulp, 2006). IRScNB R24 IRScNB R24 (Fig. 2A-D) is a complete