The early Paleogene was marked by apparent
diversification in several vertebrate clades following the
end-Cretaceous extinction. However, gaps in the early
Paleocene (Danian) record for many groups are an
obstacle to testing competing models of extinction and
recovery. This problem is particularly acute for
percomorph (perch-like) teleost fishes, a clade containing
over 14,000 living species. While diverse marine fish
assemblages are known from the Late Cretaceous (e.g.,
Nardò, Italy) and the early Eocene (e.g., Danata
Formation, Turkmenistan), the record of articulated
material from the critical Danian interval is restricted to
only a handful of sites worldwide. We report a horizon in
Gebel Qreiya in the Eastern Desert of Egypt that provides
new information on paleotropical (~9°N paleolatitude)
marine fishes from the southern Tethys. The fossils occur
in the top part of the Dakhla Formation in a dark
laminated marl marking the base of the Latest Danian
Event, a hyperthermal dated to 62.2 Ma. These fishbearing layers were deposited in an outer neritic to upper
bathyal setting (150–250 m). The fossils are generally
articulated and complete, with over 50 specimens
recovered during a single field visit. Most individuals
measure only a few centimeters in length. Multiple taxa
are present based on material collected to date, but the
most striking member of the fauna is the moonfish, Mene.
The fossils from the Latest Danian Event bed predate the
earliest previous occurrence of Mene by more than 5
million years, and represent the oldest example of an
articulated percomorph assignable to an extant genus.
They provide an important new temporal constraint on the
evolutionary radiation of perch-like fishes, and
demonstrate over 60 million years of remarkable
anatomical conservatism in menids. Other fishes include
an undetermined form with fan-like pelvic fins and a
long-based dorsal fin bearing elongated spines. In
addition to its critical stratigraphic position, the lowlatitude Danian Gebel Qreiya assemblage begins to fill a
paleogeographic gap in the record of articulated early
Paleogene marine fishes, which so far has been dominated
by assemblages from mid-latitude sites in Europe and
western Asia. |
