Galeocerdo aduncus ( Agassiz, 1835 )

Galeocerdo aduncus ( Agassiz, 1835)

Plate 3, Figs 35–38

* Galeus aduncus Agassiz, 1835 : pl. 26, figs 24–28.

Galeocerdo aduncus Agassiz, 1835 — Le Hon 1871: 9.

Galeocerdo aduncus (Agassiz) — Zbyszewski & Almeida 1950: 343, pl. 6, figs 102, 103, 105, 106, 109, 110. Galeocerdo aduncus Agassiz, 1843 [ sic]— Antunes & Jonet 1970: 165, pl. 11, figs 59–62.

Galeocerdo aduncus Agassiz, 1835 — Cappetta 1970: 50, pl. 12, figs 1, 2.

Galeocerdo aduncus Agassiz— Antunes et al. 1981: 18 , pl. 2, figs 10, 13.

Galeocerdo aduncus Agassiz, 1843 [ sic]— Balbino 1995: 86, pl. 16, fig. 1.

Galeocerdo aduncus Agassiz, 1843 [ sic]— Müller 1999: 50, pl. 10, figs 1–8.

Galeocerdo sp. — Purdy et al. 2001: 145, text-figs 48b, e, 49.

Galeocerdo aduncus Agassiz, 1843 [ sic]— Antunes & Balbino 2004: 85, fig. 6e.

Galeocerdo aduncus Agassiz, 1835 — Cappetta 2012: 298.

Galeocerdo aduncus ( Agassiz, 1835) — Schultz 2013: 84, pl. 7, figs 11a, b, 12a, b.

Galeocerdo aduncus Agassiz, 1835 — Fialho et al. 2021: 416, figs 6c–d.

Galeocerdo aduncus Agassiz, 1835 — Fialho 2022: 122, pl. 5, fig. B.

Material. Ten isolated teeth. NHMW 2025 View Materials /0177/0014 ( 4 specimens) .

Description. The species is monognathic heterodont. There is a slight difference in the curving of the principal cusp that is more curved in lower teeth than in upper ones in the extant Galeocerdo cuvier (Perron & LeSueur, 1822) . The upper teeth ( Pl. 3, figs 35a–36b). The remaining specimens ( Pl. 3, figs 37a–38b) are lower teeth. The first tooth ( Pl. 3, figs 35a–b) possesses a strongly curved principal cusp at an angle of 50°. The slightly concave distal cutting edge is smooth and a distal blade, separated by a notch, bears a fine serration. The mesial cutting edge has a fine serration at its lower end. The root is divided into two root lobes by a shallow central groove that diverge at an angle of 90°. The distal lobe is significantly wider than the mesial one. The second tooth ( Pl. 3, figs 36a–b) is severely damaged at the crown that lacks a large part of the mesial cutting edge. The principal cusp is curved distally at an angle of 50°. The slightly convex distal cutting edge is smooth and a distal blade, separated by a notch, has a fine serration. The mesial cutting edge has a fine serration. The root is divided into two equally sized root lobes by a shallow central groove that diverge at an angle of 50°. The third tooth ( Pl. 3, figs 37a–b) is from an almost lateral position with a principal cusp curved at 30°. The slightly convex distal cutting edge is smooth and a distal blade, separated by a notch, has a fine serration. The convex mesial cutting edge bears a fine serration at its lower end. A series of up to six small distal cusplets are present that gradually diminish in size. The root is divided into two root lobes by a shallow central groove, the distal one slightly wider than the mesial one. The fourth tooth ( Pl. 3, figs 38a–b) is positioned further laterally with a stronger curved principal cusp at an angle of 45° and a convex mesial cutting edge bearing a fine serration at the lower end. The slightly convex distal cutting edge is smooth and a distal blade, separated by a notch, has a fine serration. The root is divided into two root lobes by a shallow central groove, the distal one slightly wider than the mesial one.

Discussion. The fossilised teeth of Galeocerdo aduncus are found worldwide in Neogene neritic sediments. They show many similarities with the dentition of the extant Galeocerdo cuvier (Perron & LeSueur, 1822) . However, C. aduncus still is used by all authors for Miocene fossil material and we follow those authors. After García et al. (2011), Galeocerdo , is a thermophilic taxon. Today, populations of the only extant species of Galeocerdo , G. cuvier , the Tiger Shark, is found worldwide in tropical and subtropical waters.

Distribution. Oligocene–Lower Miocene: North Sea Basin, nort-west Germany ( Schultz 2013). Lower Miocene: Atlantic, France ( Schultz 2013). Lower-Middle Miocene: Paratethys, Austria ( Schultz 2013). Miocene: Proto-Mediterranean, Italy, Malta, southern France ( Cappetta 1987; Schultz 2013). Miocene (indeterminate): Florida, USA ( Perez 2022), Cuba, Argentina, Angola, Zaire, Ecuador, Japan, India ( Cappetta 1987; Müller 1999; Schultz 2013). Pliocene: Florida USA ( Perez 2022), North Sea Basin, Belgium; Mediterranean, Italy ( Schultz 2013).

Distribution in Portugal. Lower Miocene: (Burdigalian) Lower Tagus Basin ( Zbyszewski & Almeida 1950). Middle Miocene: (Langhian-Serravallian) Lower Tagus Basin ( Zbyszewski & Almeida 1950; Serralheiro 1954; Antunes & Jonet 1970; Fialho et al. 2021); Algarve Basin, Lagos–Portimão Fm. ( Antunes et al. 1981). Upper Miocene: (Tortonian) Lower Tagus Basin ( Zbyszewski & Almeida 1950; Serralheiro 1954), Algarve Basin, Cacela Fm. (this paper); (Messinian) Alvalade Basin, Esbarrondadoiro Fm. ( Balbino 1995; Antunes & Balbino 2004).