Macrorhizodus praecursor

Taxonomy

"Mako"

Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Lamniformes
Family: Lamnidae
Genus: Macrorhizodus
Species: Macrorhizodus praecursor
Author Citation (Leriche, 1905)

Geological Time Scale

Eon: Phanerozoic
Era: Cenozoic
Period: Paleogene
Sub Period: None
Epoch: Eocene
International Age: Priabonian

Stratigraphy

Castle Hayne Formation

Provenance

Collector: Don Rideout
Date Collected: 04/10/2023
Acquired by: Field Collection

Dimensions

Length: 36 mm
Width: 23 mm

Location

Private Pit
Jones County
North Carolina
United States

• castle hayne
• eocene
• macrorhizodus praecursor
• shark
• tooth

Comments

M. praecursor is a relatively common find in vertebrate lenses of the Castle Hayne Formation. Leriche (1905) believing the species to be an Eocene version of the much younger Oxyrhina desori (Isurus desori) erected Oxyrhina desori praecursor. Leriche (1942) erected Oxyrhina praecursor americana for teeth with slightly different root and blade characteristics. These were placed into Isurus (White, 1931) and eventually a new genus, Macrorhizodus by Glickman (1964). Both praecursor and americana were accepted as distinct species (White 1956, Ward & West 1990, Zhelezko & Kozlov 1999 and Case & Borodin 2000a). Ebersole, Cicimurri & Stringer 2019 determined through studies of the extant Isurus oxyrhynchus that these different characteristics are attributable to heterodonty and placed americana as a junior synonym of praecursor. 

 

References:

 

Ebersole, Cicimurri & Stringer, 2019. Taxonomy and biostratigraphy of the elasmobranchs and bony fishes (Chondrichtyes and Osteichthyes) of the lower to middle Eocene (Ypresian to Bartonian) Clairborne Group in Alabama, USA, including an analysis of otoliths. pgs 56-58

 

as Isurus praecursor

 

Chandler, Richard 2015. Fossil Fish, Volume 3 of 4. North Carolina Fossil Club. pgs 67-68

 

Case and Borodin, 2000. A Middle Eocene Selachian Fauna from the Castle Hayne Limestone Formation of Duplin County, North Carolina. Plate 3 fig. 21-26