PEPESUCHINAE, Geroto & Bertini, 2019

Geroto, Caio Fabricio Cezar & Bertini, Reinaldo J., 2019, New material of Pepesuchus (Crocodyliformes; Mesoeucrocodylia) from the Bauru Group: implications about its phylogeny and the age of the Adamantina Formation, Zoological Journal of the Linnean Society 185, pp. 312-334 : 330-331

PEPESUCHINAE SUBFAM. NOV.

urn:lsid:zoobank.org:act:9429A610-2185-4000-AF39-B6F7A550C887

Diagnosis

Crocodyliforms with an elongated platirostral rostrum, parallel lateral edges of the nasals and maxilla–lacrimal contact fully included in the antorbital fossa. The anterior wedge portion of the frontal region is elongated and inserted between the nasals; the nasals have a posterolateral process inserted between the prefrontals and lacrimals. The lateral aspect of the longitudinal axial inclination of the humeral shaft is slightly posterodorsally inclined.

Etymology

Pepesuchinae was established as the name of the subfamily based on P. deiseae Campos et al., 2011 .

Phylogenetic definition

Pepesuchus deiseae and all Crocodyliformes that share a more recent common ancestor with P. deiseae than with N. terrestris Woodward, 1896 , S. icaeorhinus Simpson, 1937 , B. pachecoi Price, 1945 , S. huenei Price, 1950 , P. torminni Price, 1955 , G. peirosauroides ( Gasparini et al., 1991) , L. palpebrosus Gasparini et al., 1991 , M. arrudacamposi Carvalho et al., 2007 , A. gomesii Price, 1959 , Malawisuchus mwakasyungutiensis Gomani, 1997 , M. amarali Carvalho & Bertini, 1999 , and C. niloticus Laurent, 1768 .

Discussion

This phylogenetic analysis revealed a monophyletic clade comprising C. camposi , B. franciscoi , I. jesuinoi , P. deiseae and MCT 1723-R, and excluding Miadanasuchus oblita and A. minor , making the clade Trematochampsidae paraphyletic, sensu Buffetaut (1991). Pepesuchinae has phylogenetic stability as a name for this group and was recovered in further analyses as a polytomy ( Montefeltro et al., 2013); internal relationships were recovered and solved. The clade definition contains P. deiseae as an internal specifier because the taxon is more preserved than I. jesuinoi , with P. torminni as an external specifier, allowing the clade to remain stable even with changes in the phylogenetic position of P. torminni .

This group is supported by ten synapomorphies as follows: posterolateral nasal process inserted between the prefrontal and lacrimal (54.1); a longer total lacrimal length relative to total prefrontal length (57.0); a rod-shaped jugal below the laterotemporal fenestra (65.1); an anterior margin of the prefrontals at the same level as the frontal anterior margin (70.1); a slightly depressed nasal–frontal contact area (80.1); an anterior process of the frontal extending between the prefrontals (82.1); a postorbital bar inclined medially and posteroventrally (95.1); mandibular branching with anteroposterior axis twice the medial–lateral width in the dorsal view (that forms a Y shape) (187.2); an anterior dentary direction of the teeth that is slightly procumbent (240.1); no internarial bar (250.2).

THE AGE OF THE ADAMANTINA FORMATION

Time calibration of the phylogenetic hypotheses described above implies that Pepesuchinae originated from an Early Cretaceous ancestry. The presence of early members of the clade from the Araripe Basin suggests an origin there. A subsequent cladogenic event split this group into two lineages, the first giving rise to C. camposi , and the other spreading to the Bauru Group and giving rise to some of its taxa ( Itasuchus , Pepesuchus and Barreirosuchus ). A palaeobiogeographical link has been suggested between the Araripe and Paraná basins, although these crocodyliform taxa cannot be used to correlate these localities. Except for C. camposi , found in the Lower Cretaceous of the Araripe Basin, all other taxa included in Pepesuchinae occur in the Upper Cretaceous Bauru Group.

The phylogenetic results show that diversification within itasuchine taxa from the Bauru Group occurred throughout the Santonian, matching the stage during which depositions and basin border rising occurred in the region ( Riccomini, 1997; Batezelli et al., 2003). Both Peirosaurinae and Pepesuchinae can be found in the Adamantina and Marília Formations.

Itasuchus jesuinoi occurs in two localities and in distinct geological units: the Adamantina ( Mezzalira, 1989) and Marília Formations ( Price, 1955). Pepesuchus deiseae and B. franciscoi also occur in the Adamantina Formation ( Campos et al., 2011; Iori & Garcia, 2012). Peirosauridae occurs in outcrops from the Adamantina Formation, considering the presence of Montealtosuchus ( Carvalho et al., 2007) , and in the Marília Formation, considering the presence of P. torminni ( Price, 1955; Carvalho et al., 2004).

The morphological similarity between Pepesuchinae taxa from the Adamantina and Marília Formations, and the occurrence of the same species in both, reveals a close chronology for these geological units. The age of the Marília Formation is usually considered Maastrichtian owing to the presence of charophytes, ostracods, turtles and dinosaurs ( Dias-Brito et al., 2001; Gobbo-Rodrigues et al., 2001; Santucci & Bertini, 2001; Menegazzo, Bertini & Manzini, 2015).

Another faunal correlation can be determined between the Adamantina and Santo Anastácio Formations. The presence of a podocnemidid in both geological units derived from Early Cretaceous taxa ( Menegazzo et al., 2015). Menegazzo et al. (2016) suggests a Coniacian age for the Santo Anastácio Formation.

The Adamantina and Araçatuba Formations from the Bauru Group and the Locoche and Bajo de La Carpa Formations from the Neuquén Group can be dated to the Campanian–Maastrichtian ages ( Leanza & Novas, 2004) considering assemblages of ostracods such as Ilyocipris argentinensis, I. riogradensis ( Gobbo-Rodrigues et al., 1999a, b; Carignano & Varela, 2011) and Vecticipris sp. ( Dias-Brito et al., 2001; Carignano & Varela, 2011). There are similarities between the aeolosaurine Brasilotitan nemaphagus from the Adamantina Formation and Antarctasaurus whichmannianus and Bonitasaura salgadoi from the Santonian of Argentina ( Machado et al., 2013). Mariliasuchus material has been found in the lower layers of the Adamantina Formation , in contact with the Araçatuba Formation, which is dated as Coniacian–early Santonian ( Andrade & Bertini, 2008; Menegazzo et al., 2016). These correlations and the distribution of some morphotypes along the same time span in these geological units point to at least a Campanian age for the Adamantina Formation , possibly Campanian–Maastrichtian. Supporting this hypothesis, there are morphological similarities between crocodyliform taxa from those geological units, as proposed by Bertini et al. (2001), Gobbo-Rodrigues et al. (1999a, b) and Santucci & Bertini (2001), in opposition to the Turonian to Santonian proposal of Castro et al. (1999) and Dias- Brito et al. (2001).

CONCLUSIONS

The new data provided by Pepesuchus MCT 1723 -R, regarding taxa closely related to I. jesuinoi , generates phylogenetic stability and is a significant addition to the fossil record from the Bauru Group. MCT 1723-R shares synapomorphies with P. deiseae that allow the specimen to be inserted in the Pepesuchus genus. These synapomorphies include the dorsal edge of the rostrum starting from the anterior verge of the concave orbits and the L-shaped lacrimal inferior process contacting the jugal.

The differences between P. deiseae and Pepesuchus MCT 1723 -R cannot be determined as taxonomic or intraspecific variation, because there are few specimens of Pepesuchus MCT 1723 -R, and the material is in a fragmented state.

The description of MCT 1723-R indicates characteristics that solved internal relationships among Itasuchus, Pepesuchusxi and Barreirosuchus , with polytomies prior to the addition of the MCT 1723-R material. Two characteristic suture patterns occur in Pepesuchinae : the insertion of the frontals into the anterior region between the nasals, and a posterolateral process inserting between the prefrontal and lacrimal. The frontal inserted between the prefrontal is a diagnostic characteristic that appears as a synapomorphy from a more inclusive group, containing taxa from both the Adamantina and Marília formations. The fact that distinct geological units show not only species with morphological similarities, but also the occurrence of the same genus in both geological units, points to the correlation of their ages and the placement of the Adamantina Formation in the Campanian–Maastrichtian interval.