Y.M. Alves, L.P. Bergqvist, & P.M. Brito. 2016. New occurrences of microvertebrate fossil accumulations in Bauru Group, Late Cretaceous of western Sao Paulo state, Brazil. Journal of South American Earth Sciences, 69, pp. 80–90. doi:10.1016/j.jsames.2016.03.003
Alves et al. wrote:ABSTRACT
In this work, we present the results of several palaeontological expeditions to four Upper Cretaceous fossil microsites of the Adamantina and Presidente Prudente formations in western São Paulo State, Brazil. Despite the fragmentary condition of the fossils recovered, they represent an important record of vertebrate microremains. The material, recovered through screen washing, comprises teeth and scales of Lepisosteidae; two morphotypes of Halecostomi teeth with similarities to Characiformes and Amiiformes; a Teleostei tooth of molariform shape; fin spines of Siluriformes; teeth of possible Baurusuchidae, Notosuchia (probably Adamantinasuchus or Mariliasuchus), Neosuchia (probably Itasuchus or Goniopholis), and other Mesoeucrocodylia indet.; probable teeth of Abelisauroidea, other Theropoda indet., and a phalanx of Aves. The comparative microvertebrate fossil accumulation from western São Paulo State provides evidence that: 1) floodplain channels accumulate large concentrations of microremains; 2) coarse sandstone privileges enamel tissues like teeth and scales; 3) new vertebrate fossil records have been discovered in Florida Paulista, Alfredo Marcondes, and Alvares Machado outcrops.
From the paper:
Alves et al. wrote:4.1.4.1. Material. Three incomplete fin spines and one articular portion (head) of pectoral-fin spine.
Three spine fragments comprise the distal portion of dorsal or pectoral fin spines. They are all dorso-ventrally compressed with irregular longitudinal striations in lateral view and present dentations on the posterior edge inside a longitudinal groove. The dentations here are compressed, enlarged, retrorse, hooked, and irregularly spaced.
The [one specimen], despite being incomplete, presents a preserved articular head. The dorsal process is eroded with rectangular shape, for articulation with the spinal fossa. Behind it, in this view, are two other processes: ventral and anterior in a U-shape. Distally, the spine head importantly presents a narrow and deep basal recess and a morphological character distinct from the spines presented by Gayet and Brito (1989) and Bertini et al. (1993).
4.1.4.3. Discussion. These fin spines are distinctive specimens belonging to Siluriformes and several papers illustrate them (see Cione, 1987; Gayet and Brito, 1989; Martinelli and Forasiepi, 2004). We are currently preparing a paper focussing a comparative analysis among fossil fin spines of Bauru Group with extant catfish forms. What we can say so far is that in the morphology presented here only two things are relevant for comparison with other pectoral catfishes: 1) the absence of dentations in the anterior section; 2) the shape of posterior dentations (compressed, enlarged, retrorse, regular, and hooked). The first are found only for Diplomystidae (see Arratia,1987) and any genus of Bagridae (see de Pinna, 1998). The second again have similarities with Diplomystidae and Bagridae but also with any Pimelodinae too. We think that there is little information to assign this material to a more inclusive taxon of Siluriformes. (emphasis added by Eric)
4.1.4.4. Remarks. Cretaceous freshwater Siluriformes are known in South America only from fragmentary and isolated remains of pectoral and dorsal-fin spines. They are reported in the Late Cretaceous Yacoraite Formation (Cione et al., 1984), Coli Toro, Los Alamitos, La Colonia (Cione and Laffite, 1980; Cione, 1987; Bovcon, 2002), and Allen (Martinelli and Forasiepi, 2004) formations in Argentina, the El Molino Formation (Gayet et al., 2001) in Bolivia, and the Bauru Group (Gayet and Brito, 1989; Brito et al., 2006) in Brazil. Outside South America, Siluriformes are also known from the Maastrichtian of Niger (Patterson, 1993), Spain (de la Pena and Soler-Guijon, 1995), India (Cione and Prasad, 2002), and possibly the United States (Frizzel and Koenig, 1973).
If the Adamantina Formation is Turonian-Santonian in age, the Siluriformes remains occurring in the Jales outcrop are the oldest in the world.
