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| Mimodactylus libanensis
Kellner, Caldwell, Holgado, Dalla Vecchia, Nohra, Sayão & Currie, 2019
Artwork of Julius T. Csotonyi.
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Abstract
Despite being known from every continent, the geological record of pterosaurs, the first group of vertebrates to develop powered flight, is very uneven, with only a few deposits accounting for the vast majority of specimens and almost half of the taxonomic diversity. Among the regions that stand out for the greatest gaps of knowledge regarding these flying reptiles, is the Afro-Arabian continent, which has yielded only a small number of very fragmentary and incomplete materials. Here we fill part of that gap and report on the most complete pterosaur recovered from this continent, more specifically from the Late Cretaceous (~95 mya) Hjoûla Lagerstätte of Lebanon. This deposit is known since the Middle Ages for the exquisitely preserved fishes and invertebrates, but not for tetrapods, which are exceedingly rare. Mimodactylus libanensis gen. et sp. nov. differs from the other Afro-Arabian pterosaur species named to date and is closely related to the Chinese species Haopterus gracilis, forming a new clade of derived toothed pterosaurs. Mimodactylidae clade nov. groups species that are related to Istiodactylidae, jointly designated as Istiodactyliformes (clade nov.). Istiodactyliforms were previously documented only in Early Cretaceous sites from Europe and Asia, with Mimodactylus libanensis the first record in Gondwana.
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| Figure 1: Geographical location where the new pterosaur, Mimodactylus libanensis gen. et sp. nov., was collected. (a) Geological map of Lebanon (adapted from Dubertret, 1955). (b) Detail showing the location of the most important fossil Lagerstätten of Lebanon (modified from Dalla Vecchia et al., 2002). (c) Position of Lebanon in the broad carbonate platform that surrounded the northern part of the Afro-Arabian continent during the late Cenomanian (modified from Philip and Floquet, 2000).
Abbreviations. a = Apulian Carbonate Platform (southern Italy); acp = Adriatic Carbonate Platform (Italy, Slovenia, Croatia); bd = Bei Daglari (Turkey); bih = Bihor Massif (Romania); bm = Bohemian Massif (Central Europe); et = Eastern Taurus (Turkey); g = Gavrovo (Greece); gm = Golija Massif (Serbia); inm = Insubrian Massif (Alps); sy = Seydisehir (Turkey); uks = Ukrainian Shield (Ukraine). The yellow star indicated on each map the location of the Hjoûla Lagerstätte(a,b), whilst the red asterisk Lebanon(c).
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| Reconstructed silouette of Mimodactylus libanensis showing the long wings regards the body.
Scale bar: 50 mm.
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Systematic palaeontology
Pterosauria Kaup, 1834.
Pterodactyloidea Plieninger, 1901.
Ornithocheiroidea Seeley, 1870 sensu Kellner (2003).
Pteranodontoidea Marsh, 1876 sensu Kellner (2003).
Lanceodontia Andres et al., 2014.
Istiodactyliformes clade nov.
Branch-based definition: The most inclusive clade containing Istiodactylus latidens, but not Anhanguera blittersdorffi.
Diagnosis: Slender-built lanceodontian pterodactyloids with the following synapomorphies: mandibular rostral end pointed, teeth confined to the anterior half of the jaws, and labiolingually compressed crowns with a cingulum.
Included taxa: Istiodactylidae, Mimodactylidae, and Hongshanopterus lacustris.
Mimodactylidae clade nov.
Branch-based definition: The most inclusive clade containing Mimodactylus libanensis gen. et sp. nov., but not Istiodactylus latidens, Ikrandraco avatar, and Anhanguera blittersdorffi.
Diagnosis: Istiodactyliforms with cone-shaped teeth, crowns with a slight labiolingual compression, and sternal articular surface of the coracoid slightly concave.
Included species: Haopterus gracilis and Mimodactylus libanensis gen. et sp. nov.
Mimodactylus libanensis gen. et sp. nov.
Etymology: Mimodactylus, from the acronym MIM (Mineral Museum) for the museum housing the specimen, in recognition of both the museum and the wishes of the anonymous philanthropist who facilitated the acquisition of the specimen thus keeping it in Lebanon, and the Greek ‘dactylos’ (δάκτυλος), meaning digit; libanensis from Lebanon, where the specimen was found.
Holotype: Almost complete skeleton, including the skull and lower jaw, housed at the Mineral Museum (MIM) of Beirut, Lebanon, MIM F1. Cast at the University of Alberta, Edmonton and Museu Nacional/UFRJ (MN 7216-V).
Locality and horizon: Hjoûla Lagerstätte of the Sannine Limestone (late Cenomanian), near the town of Hjoûla located 35 km NNE of Beirut and 10 km inland from Jbail, Lebanon.
Diagnosis: Mimodactylid with the following autapomorphies: humerus with a rectangular deltopectoral crest; humerus smaller than half the length of the second phalanx of the wing finger (hu/ph2d4 < 0.5). This species can be further distinguished from other ornithocheiroid pterodactyloids by the following combination of characters: discrete palatal ridge; 11 and 10 cone-shaped teeth on each side of the upper and lower jaws, respectively; scapula slightly longer than coracoid; humerus much longer than femur (hu/fe ~1.3); deltopectoral crest extends for around 40% of the humerus shaft length (see Supplementary Information for further details and measurements).
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| Life reconstruction of Mimodactylus libanensis gen. et sp. nov.
Artwork of Julius T. Csotonyi.
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| Phylogenetic relationships of Mimodactylus libanensis gen. et sp. nov. within Ornithocheiroidea. Colours show their continental origin: Afro-arabia (brown), Asia (orange), Europe (red), North America (blue), and South America (green).
Outgroup relationships are not shown (see Holgado et al., 2019 and Supplementary Information for further details). Intermittent bars show uncertain temporal range. Stratigraphic chart modified from Cohen et al., 2013
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Alexander W. A. Kellner, Michael W. Caldwell, Borja Holgado, Fabio M. Dalla Vecchia, Roy Nohra, Juliana M. Sayão and Philip J. Currie. 2019. First Complete Pterosaur from the Afro-Arabian Continent: Insight Into Pterodactyloid Diversity. Scientific Reports. 9, 17875. DOI: 10.1038/s41598-019-54042-z
