Maaradactylus kellneri, Bantim & Saraiva & Oliveira & Sayão, 2014

Bantim, Renan A. M., Saraiva, Antônio A. F., Oliveira, Gustavo R. & Sayão, Juliana M., 2014, A new toothed pterosaur (Pterodactyloidea: Anhangueridae) from the Early Cretaceous Romualdo Formation, NE Brazil, Zootaxa 3869 (3), pp. 201-223 : 204-207

Maaradactylus kellneri gen. et sp. nov.

Holotype. Holotype deposited in the Museu de Paleontologia da Universidade Regional do Cariri ( MPSC R 2357 ), Santana do Cariri-Ceará. A nearly complete skull of toothed pterosaur ( Fig. 3 ). A complete cast of the holotype is deposited in the Laboratório de Biodiversidade do Nordeste ( CAV 0014 ), Centro Acadêmico de Vitória / Universidade Federal de Pernambuco, Vitória de Santo Antão-Pernambuco .

Type locality and horizon: São Gonçalo site, Santana do Cariri city, Ceará state, Brazil (07 º 10 '54 "S 39 ° 43' 06" W and UTM 926,286 , with 596 m of altitude). Stratigraphic unit: Romualdo Formation, Santana Group, Araripe Basin. Age: Early Cretaceous-Aptian /Albian .

Etymology. The genus Maaradactylus comes from a mythical legend of the Cariri Indian tribe who lived in lakes which now correspond to the Araripe Basin (Araripe plateau). Maara was a princess who was ordered to live forever in the form of a monster attacking fishermen at night; dactylus, finger, traditionally used to denote pterosaur taxa. The specific epithet “ kellneri ”, is in honor of Dr. Alexander Wilhelm Armin Kellner, due to his efforts driving the growth of Brazilian paleontology and studies involving the systematics of pterosaurs.

Diagnosis. Presence of at least 35 pairs of alveoli in the skull. Premaxillary sagittal crest beginning at the anterior part of the skull (rostrum) and extending to the 22 nd pair of alveoli, not covering the nasoantorbital fenestra nor the choanae. Moderate palatal ridge, starting on the 5 th pair of alveoli and ending on the 13 th pair, which is less developed than in Tropeognathus but more so than in Anhanguera . Palate with convex shape in the anterior portion. Choanae not extending laterally. Small and convex palatal elevation in anterior portion of the skull. The 5 th, 6 th and 7 th alveoli smaller than the 4 th and 8 th. The alveoli decreasing in size from the 9 th to the 12 th and increasing from the 13 th to 18 th, and from the 18 th to the 35 th they are arranged in triplets.

Description and Comparisons. The holotype of Maaradactylus kellneri gen. et sp. nov. is preserved threedimensionally in a calcareous concretion, fragmented in five parts. Some bones are partially eroded, especially on the right side of the skull and the dorsal edge of the premaxillary crest, indicating that these portions in MPSC R 2357 were exposed for a long time before collection. The skull is elongated, having a high and long sagittal premaxillary crest ending before the anterior portion of the nasoantorbital fenestra. The anterior part of the skull expands laterally in a spoon shape, typical of anhanguerids. The rostrum is rounded and contains two alveoli, which are situated in a higher position than the subsequent alveoli. The dentition is constituted by at least 35 pairs of alveoli, which increase their spacing towards the posterior direction. The maxilla is incomplete and displaced, which may mean that this specimen could have had more teeth. The frontals in Maaradactylus kellneri are unfused. The contact between the premaxilla and maxilla in M. kellneri extends from 6 th pair of alveoli to the most anterior portion of the nasoantorbital fenestra. This suture is also present in other anhanguerid pterosaurs, such as Anhanguera santanae Wellnhofer, 1985 (AMNH 22555, BSP 1 982 190) and Anhanguera piscator Kellner and Tomida 2000 (NSM-PV 19892) ( Wellnhofer 1991b; Kellner and Tomida, 2000). The anterior margin of the premaxilla is rounded, different from Coloborhyncus clavirostris Owen, 1874 and Uktenadactylus wadleighi Lee, 1994 , which have an anterior margin that is flattened, forming almost a right angle with the ventral margin ( Rodrigues and Kellner 2008, 2013).

The sagittal premaxillary crest has a maximum height of 92 mm, and in dorsal view, the anterior border of the premaxilla extend laterally forming a triangular shape. This crest begins at the first pair of alveoli (most anterior end of the rostrum) as in Tropeognathus , another genus that has a premaxillary sagittal crest located at the anterior portion of the skull. However, in Maaradactylus kellneri it extends at least until the 22 nd pair of premaxillary alveoli, with a total length of 285mm; in Tropeognathus it is shorter, extending only to the 9 th alveoli. In other anhanguerids such as Siroccopteryx moroccensis Mader and Kellner, 2003 , Uktenadactylus wadleighi and all species of the genus Anhanguera , the premaxillary crest begins more posteriorly than in Maaradactylus kellneri and Tropeognathus . Furthermore the lateral surface of the premaxillary crest possesses grooves and tridimensional structures which may have housed blood vessels. The maxilla is elongate, approximately 405mm in length, and comprises a significant portion of the ventral part of the skull. It is fully preserved though slightly compressed laterally, probably during fossilization. This has displaced and obscured some elements, causing a slight shortening whose exact proportions cannot be defined. In the ventral view, the maxilla is slightly curved upward, starting approximately at the 5 th alveoli, as is observed in Anhanguera spielbergi Veldmeijer, 2003 , Anhanguera santanae and Anhanguera piscator . In ventral view the opening of the nasoantorbital fenestra and an elevation of the palate can be seen, which become more evident in the anterior portion of the premaxilla, between the 5 th and 8 th alveoli.

As common for pterodactyloids, the nasoantorbital fenestra occupies a considerable part of the skull, reaching about 40% of the preserved portion. Its total length is approximately 100 mm and maximum height 109 mm. In ventral view, the fenestra is partially preserved, with its limits distorted due to the dislocation of the maxilla, jugal and quadrate.

The jugal forms the lower basis of nasoantorbital fenestra, orbit and temporal opening. The contact among the jugal and quadratojugal cannot be observed. The jugal forms a straight angle at the base of the nasoantorbital fenestra, narrowing toward the maxilla, ending in a thin bone. Its overall shape is similar to that of other anhanguerids. The maxillary process of M. kellneri is long and thin as in Anhanguera piscator ( Kellner and Tomida 2000) .

In M. kellneri only the left quadrate is preserved, but it has been displaced. The quadrate is a robust bone as in other anhanguerids. It is fused with the jugal, forming a cohesive structure with no visible suture. No articulation can be identified with the squamosal, because this bone is not preserved, as well as other bones of the posterior region of the skull, such as the basisphenoid, laterosphenoid and postorbital. The supraorbital is a thin bone blade flattened dorsoventrally, which is the smallest bone in the dorsal portion of the skull. This bone has a similar morphology among all anhanguerids, as it is triangular and overlaps the posterior part of the prefrontal. The contact between this bone and the premaxilla is not preserved in M. kellneri .

Along the midline, the frontals are unfused. The medial suture between the left and right sides is well developed, forming a shallow groove that runs towards the parietal. The contact surface of the frontal with the postorbital is not preserved. There is a small crest in the posterior region of the skull, formed by the contact of the frontal with the parietal. The exact length of this crest cannot be determined in MPSC R 2357, but this structure is similar to that in the Anhanguera species , in contrast to the quite robust crest in Tropeognathus . The crest in the holotype of Anhanguera santanae is longer, whereas in Anhanguera blittersdorffi Campos and Kellner, 1985 , Anhanguera araripensis Wellnhofer, 1985 , Anhanguera piscator and Anhanguera spielbergi is short.

Maaradactylus kellneri has at least 35 pairs of alveoli, but only five alveoli preserve teeth. In the anterior portion, the alveoli are well preserved, but towards the posterior region they are weathered, especially on the left side. Except for the first pair, which is at a higher level than the second, all the alveoli are oriented ventrally ( Fig. 4a,c ). This characteristic is shared by most toothed pterosaurs from the Santana Group, including all species of Anhanguera , Tropeognathus mesembrinus Wellnhofer, 1987 and Ludodactylus sibbicki Frey, Martill and Buchy, 2003 ( Rodrigues and Kellner 2008). Other anhanguerids also share this condition ( Campos and Kellner 1985; Kellner 2003; Rodrigues and Kellner 2008; Martill and Unwin 2012), as does " Ornithocheirus " sedgwickii ( Owen, 1859) and " Ornithocheirus " cuvieri ( Bowerbank, 1851), Caulkicephalus trimicrodon Steel, Martill, Unwin and Winch, 2005 , Siroccopteryx moroccensis and Uktenadactylus wadleighi .

The first alveolus has a reduced size (5mm), similar to the condition present in other anhanguerids. The second alveolus is larger than the first, but smaller than the third and fourth. The third and fourth alveoli are larger (12mm and 13mm, respectively). Three smaller alveoli of similar size are present after the 4 th alveoli: the 5 th, 6 th and 7 th alveoli are smaller than the 4 th and 8 th ( Fig. 4b,d ). From the 9 th to the 12 th positions, the alveoli decrease in size, and from the 13 th to the 18 th they increase in size again. The alveoli are arranged in triplets from the 18 th to the 35 th. These are arranged linearly and each triplet is separated by about 3 to 4 cm (an exclusive characteristic of M. kellneri ).

The dentition of Pterodactyloidea shows some specializations, with teeth varying in shape, number and disposition within the jaws. This variation includes taxa with hundreds of tiny elongated teeth, such as Ctenochasma ( Bennett 2007) and Pterodaustro ( Chiappe and Chinsamy 1996) , and taxa with a reduced number of teeth, as seen in Tropeognathus ( Kellner et al. 2013) . Other lineages possess a very specialized and unique dentition, like Dsungaripteridae , where the anterior parts of the upper jaws are toothless ( Lü et al. 2009). In this group the distance between teeth is greater in the middle portion of the dentition than in the anterior and posterior portions of the upper and lower jaws, where the space between teeth is shorter ( Lü et al. 2009). Maaradactylus kellneri has the highest number of alveoli of all anhanguerids and related taxa. Regarding the genus Anhanguera , the species with the closest alveoli count to Maaradactylus kellneri is Anhanguera blittersdorffi , which has 26 pairs in the holotype (MN 4805-V) and 22 in a referred specimen (n. 40 Pz-DBAV-UERJ). Anhanguera santanae and Anhanguera piscator both have 20 pairs. Anhanguera spielbergi and Anhanguera araripensis (specimen MN 4735-V) show even fewer alveoli, with 18 pairs each. In Cearadactylus ? ligabuei Dalla Vecchia, 1993 there are 22 pairs, while Cearadactylus atrox Leonardi and Borgomanero, 1985 has 16 pairs. The most limited dentition is in Tropeognathus mesembrinus Wellnhofer, 1987 , which has only 14 pairs of alveoli.

The palatine contacts the maxilla laterally, and subsequently limits the opening of the choanae. Posterior to this is a relatively low sagittal ridge, beginning at the 5 th alveoli and ending at the 12 th. Other anhanguerids also have this structure, such as Anhanguera blittersdorffi , whose palatal ridge extends posteriorly until the anterior border of the choanae and anteriorly to the expansion of the premaxilla, disappearing between the 4 th and 5 th alveoli. Anhanguera araripensis also has a small ridge on the palate, which starts at the 9 th alveoli and ends at the 12 th alveoli. In Anhanguera santanae the palatal ridge is most evident at the 6 th alveoli, and in Anhanguera spielbergi it is more tenuous, positioning itself between the 5 th and 10 th alveoli. In Tropeognathus mesembrinus the palatal ridge is extremely high and robust, the largest among anhanguerids.

Figures

FIGURE 3. The holotype of Maaradactylus kellneri gen. et sp. nov. (MPSC R 2357) from the Romualdo Formation, Araripe basin, Brazil. a, reconstruction, with shaded areas representing unpreserved parts. b, photograph. c, drawing. Abbreviations: f, frontal; fcr, frontal crest; j, jugal; m, maxilla; naof, nasoantorbital fenestra; or, orbit; p, parietal; pcr, parietal crest; pm, premaxilla; pmcr, premaxillary crest; sor, supraorbital; sut, suture; tht, teeth. Scale bar=100mm.

FIGURE 4. The holotype of Maaradactylus kellneri gen. et sp. nov. (MPSC R 2357) from the Romualdo Formation, Araripe basin, Brazil. a,c, anterior view (notes the first pair of alveoli in a higher position). b,d, ventral view. Abbreviations: alv, alveoli; ch, choana; m, maxilla; pl, palatine; prid, palatal ridge; pmcr, premaxillary crest; s, sulcus; tht, teeth; v, vomer. Scale bar=50mm.