Osteoglossid and Lepisosteid Fish Remains From the Paleocene Palana Formation, Rajasthan, India

Abstract

A new fossil osteoglossid fish, Taverneichthys bikanericus gen. et sp. nov. and an unnamed but probable new species of ?Lepisosteus (Lepisosteidae) are described from the subsurface beds of the Palana (lignite) Formation near Bikaner, western Rajasthan, India. T. bikanericus is founded on a skull, which is the first osteoglossid skull from the Indian subcontinent, whereas ?Lepisosteus sp. is represented by a part of its trunk covered with ganoid scales. The taxonomic assignment of the latter specimen to gars is based on the micro-and ultrastructure of its scales. Taverneichthys is included in the Osteoglossinae because it shares at least three of the seven diagnostic characters of the subfamily: (1) jaw articulation behind the vertical midline of orbit, (2) palatine and ectopterygoid fused to form palato-ectopterygoid, and (3) horizontal arm of preopercle short, ending anteriorly behind orbit (inferred). It is characterized by a considerably larger dermethmoid bone and the two nasals that are in contact with each other behind it separating this bone from the frontals. In this respect it is more evolved than Cretophareodus and Phareodus, and closer to Brychaetus, Musperia, Opsithrissops and modern osteoglossids. The fossils documented herein are the first vertebrate remains from the Palana Formation. They were recovered from a highly indurated greyish-black calcareous shale approximately 90 m below ground level from a dug-well section. The occurrence of fossil remains of osteoglossid and lepisosteid fish in the Palana Formation, both of which are among the major predators of a terrestrial aquatic community, and their association with the crocodilian remains, are indicative of the mature and diverse nature of the Palana vertebrate community. It postulates the recovery of a varied assemblage of vertebrates, especially fish and crocodilians and possibly also mammals. The association of osteoglossid and lepisosteid fish characterizes a dominantly freshwater deposit and is consistent with a Paleocene age for the Palana Formation. The known distribution of fossil and living osteoglossid and lepisosteid fish suggests a marked shift in their climatic adaptability in time and space. Their close association in the fossil record, especially in the Indian subcontinent, is well documented, but today they thrive in different climatic zones.

Osteichthyans from an Arkadelphia Formation–Midway Group lag deposit (Late Maastrichtian–Paleocene), Hot Spring County, Arkansas, U.S.A.

“…7Q-T) bear some resemblance to those seen in Osteoglossiformes and Amiiformes. Both of these orders are known to occur in the Upper Cretaceous and throughout the Cenozoic (e.g., Santos, 1985;Gaudant, 1991;Grande and Bemis, 1998;Weems, 1999;Newbrey and Bozek, 2000;Cavin and Forey, 2001;Kumar et al, 2005;Rana et al, 2005). …”

A review of the systematic biology of fossil and living bony-tongue fishes, Osteoglossomorpha (Actinopterygii: Teleostei)

“…10), which was erected by Taverne (1979) to encompass †Phareodus (Eocene, North America, Australia, including †Phareoides), †Brychaetus, (Eocene, Europe, Africa, south Asia, and possibly North America), and †Musperia (Eocene, Sumatra). To this group can be added †Cretophareodus, †Taverneichthys, and †Ridewoodichthys (e.g., see Kumar et al, 2005;Taverne, 2009a,b;Taverne et al, 2009;Forey, Hilton, 2010). Other taxa that are referable to the subfamily, or otherwise near its base (e.g., interpreted to branch off from the stem of the family, or crownward from the phareodontines) include †Brychaetoides, †Phareodusichthys, †Monopteros, †Xosteoglossid, †Magnigena, and several unnamed taxa (Bonde, 2008;Forey, Hilton, 2010).…”

“…The fossil record documents the presence of Scleropages in Orient and in Australia in the early Eocene and Oligocene, respectively (Hills, 1934(Hills, , 1943Zhang, Wilson, 2017). Very incomplete fossils from India (Maastrichtian), Europe (Palaeocene), Sumatra (Eocene) and Africa (Palaeocene) have also been assigned to Scleropages (Kumar et al, 2005;Taverne et al, 2007;Nolf et al, 2008;Sanders, 1934;Taverne, 2009c). These fossils are all freshwater forms.…”

Testing a time hypothesis in the biogeography of the arowana genus Scleropages (Osteoglossidae)

“…Second, although Scleropages fossils are currently known from the Palaeocene of Europe (Taverne et al ., ), the Maastrichtian of India (Hora, ; Rana, ; Kumar et al ., ; Nolf et al ., ), the Eocene of Sumatra (Sanders, ; Forey & Hilton, ), the Oligocene of Australia (Hills, , ; Unmack, ) and the Maastrichtian/late Palaeocene of Africa (Taverne, ), their identifications are only tentative, because there is still no morphological synapomorphy to distinguish Scleropages from Osteoglossum (Taverne, ; Hilton, ). All fossil assignments to Scleropages are only based on overall similarity with living species (Forey & Hilton, ).…”