Allodaposuchus palustris (Blanco, Puertolas-Pascual, Marmi, Vila & Selles, 2014)

ALLODAPOSUCHUS PALUSTRIS

Localities: Els Nerets.

Material: IPS- 105939 ( MCD- 8631) ( Fig. 8A–I View Figure 8 ).

Description: The specimen is a nearly complete left mandible. The articular has not been preserved. The lateral surface of the mandible is heavily ornamented with pits and grooves.

The dentary bears 13 tooth position. The dental alveoli are circular and have similar size, with the exception of the 13 th, which is anteroposteriorly longer than wide. The fourth alveolus is the largest. Caudally to the fourth, the following largest alveolus is the 9 th. Most of the alveoli are confluent, evidencing a minimal interalveolar distance, and only the first four and the 13 th are completely septate. At the anterior dental positions, there is a series of small foramina placed lingually to the alveoli. There is a diastema between the seventh and the eighth alveoli. The rostral end of the dentary is markedly curved medially, from the fourth alveolus onwards, projecting the dentary symphysis medially to the dentary ramus. In medial view, the dentary symphysis extends posteriorly, up to the fourth alveolus. There is no external mandibular fenestra. Only a replacement tooth within the fourth alveolus has been preserved. The apex is visible in the alveolus, showing an ornamented enamel with fine ridges and false-ziphodont carinae ( Fig. 8G–I View Figure 8 ). Micro-CT scanning revealed a robust and blunt tooth hosted in the alveolus, displaying well-developed carinae with lingual grooves ( Fig. 8G View Figure 8 ). The labial surface is convex, whereas the lingual one is nearly flat. The cross-section is D-shaped because the carinae are placed lingually to the mesiodistal plane.

The splenial covers the medial surface of the mandibular ramus. The surface of the splenial is not well preserved in the central part of the bone, and there are no anterior perforations for the mandibular ramus of cranial nerve V, but it seems posteriorly perforated. At its anterior margin, the splenial is wedged and reaches the fourth alveolus, passing ventrally to the Meckelian groove with a longer ventral process but without reaching the mandibular symphysis. The Meckelian canal surpasses the anterior end of the splenial. The splenial contacts the tooth row from the ninth dental position backwards, surpassing the end of the row, and also contacts the dentary along the ventral margin.

The coronoid is boomerang-shaped and covers the anterior margin of the mandibular adductor fossa or Meckelian fossa. The anterior end of the coronoid limits the posterior half of the foramen intermandibularis medius. The medial surface of the coronoid is not well preserved and it is pushed inward due to deformation. The dorsal edge of coronoid is sloping anteriorly rather than horizontal. The ventral process of the coronoid contacts both angular and splenial. The joint of the ventral posterior ramus of the splenial with the dorsal branch of the angular prevents the coronoid to contact the foramen intermandibularis caudalis.

The angular forms the posteroventral portion of the mandible. In medial view, the foramen intermandibularis caudalis is surrounded posteriorly, ventrally and dorsally by the angular. The bone does not reach the anterior edge of the foramen intermandibularis caudalis at its dorsal margin, and this edge appears to be blunt rather than acute.

The surangular forms the posterodorsal part of the mandible. In lateral view, the suture with the angular is linear and slopes anteriorly. In medial view, the suture crosses the mandibular adductor fossa diagonally at half height. Both anterior processes of the surangular are short, being similar in length, and do not reach the last alveolus. There is no foramen between these processes.

Remarks: As in other allodaposuchids ( Blanco et al., 2014; Narváez et al., 2015, 2016), the jaw lacks external mandibular fenestra. The largest alveolus is the fourth, the mandibular symphysis reaches the fourth alveolus, the splenial does not reach the mandibular symphysis, sends an anterior process ventrally to the Meckelian canal and lacks an anterior perforation for cranial nerve V, and the angular does not extend beyond the foramen intermandibularis caudalis, ending in a blunt tip. The lineal (non-festooned) occlusal margin has been described in A. palustris and L. megadontos and differs from the condition observed in Musturzabalsuchus , Agaresuchus and the indeterminate allodaposuchid from Velaux-La Bastide Neuve ( VBN) site, but it is unknown in other taxa (i.e. A. precedens , A. hulki and A. subjuniperus ). The diastema between the seventh and the eighth alveoli is also present in Lohuecosuchus , Agaresuchus and in the VBN allodaposuchid – just as in IPS- 105939 – but in Lohuecosuchus and in the VBN form, the seventh tooth is also distanced from the sixth. Unlike IPS-105939, the coronoid completely surrounds the foramen intermandibularis medius in Agaresuchus and its superior edge is almost horizontal. The long dorsal branch of the splenial, the presence of a posterior foramen intermandibularis oralis, and the short and equal anterior surangular processes distinguish IPS-105939 from Lohuecosuchus and Agaresuchus . The number of tooth positions and the position of the largest alveolus posterior to the fourth in IPS- 105939 also differ from those counted in Lohuecosuchus , Agaresuchus and in the allodaposuchid from Velaux-La Bastide Neuve. The tooth morphology, the false ziphodonty and ornamentation are equal to those described in Allodaposuchus palustris , and differ from other allodaposuchids ( Fig. 8J–L View Figure 8 ). The tooth preserved in IPS- 105939 corresponds to morphotype IX.

IPS- 105939 was recovered associated with MCD-8389, a procoelous cervical vertebra, and MCD- 8388, the posterior end of the right mandible, which likely belong to the same individual (Supporting Information, Fig. S1A–I View Figure 1 ), and with other postcranial elements referred to the same taxon (Supporting Information, Figs S1 View Figure 1 , S 2 View Figure 2 ).