Sannine Formation

The Sannine Formation, also called the Sannine Limestone, is a Cretaceous geologic formation in Lebanon. It is a Konservat-Lagerstätte that contains a high diversity of well-preserved fish, reptiles, and invertebrates from the Tethys Ocean within its three main localities: Haqel (alternatively Hakel or Haqil), Hjoula (alternatively Hadjoula, Hajoula, or Hgula), and Nammoura (alternatively Namoura).

It is one of three major Cretaceous lagerstätte in Lebanon, alongside the older (Barremian-aged) Lebanese amber and the younger (Santonian-aged) Sahel Aalma site. The Sannine Formation localities, combined with Sahel Alma, are together referred to as the "Fish Beds" of Lebanon.

Description

It is primarily Cenomanian in age, with Haqel and Hjoula being late Cenomanian, while the slightly older Nammoura site is middle Cenomanian. Although Lebanon is now a part of Asia, the depositional environment for both formations would have been located off the coast of northern Africa during the Cretaceous, which would technically make their biota African rather than Asian.

The Cretaceous formations of Lebanon laterally vary from east to west; the western lowland "coastal" sequence (containing Sahel Aalma) is over 2000 metres thick and primarily consists of deep water limestone and chalk, while the eastern "mountain" sequence (containing the Sannine Formation) is 500–700 metres thick and consists of shallow water limestone. Two different shallow-water environments are preserved by the formation: Nammoura preserves a nearshore inner continental shelf environment with significant terrestrial input, while Haqel & Hjoula preserve an outer continental shelf environment. The neritic nature of these habitats contrasts with the other major marine lagerstätte of the region, Sahel Aalma, which is thought to have been deposited in a deepwater continental slope environment.

Pterosaur fossils have been recovered from the formation, including those of Mimodactylus and Microtuban. The pythonomorphs Pontosaurus, Eupodophis and probably Aphanizocnemus are known from the formation. Insects are also known from compression fossils, including those of a dragonfly, enigmatic pond-skater like insect Chresmoda. and a mesoblattinid cockroach. Compression fossils of angiosperm Sapindopsis are also known. Numerous species of fossil fish are known, including the ionoscopid Spathiurus dorsalis and pycnodontid Flagellipinna rhomboides. An incredible diversity of fossil pycnodonts of various, highly unusual body plans is known, in addition to the earliest representatives of modern fish groups such as acanthomorphs, African butterflyfish and eels.

History

The Sannine Formation and its fossil fishes have been known of since Roman Phoenicia. The earliest mention of them is in the Chronicon by Eusebius around 314 CE (references to earlier mentions by Herodotus are thought to be apocryphal), who mentions fossil fishes commonly being found during quarrying operations in the mountains, and cites them as evidence of the Biblical Flood. The site that these fish were recovered from is thought to correspond to the modern Haqel site. Around 1250, fossil fishes were presented to Louis IX during the Seventh Crusade and documented by Jean de Joinville, although it remains uncertain whether these originated from Haqel or the younger Sahel Alma site.

The first European to visit a Lebanese fossil fish locality in person was Cornelis de Bruijn in 1698, who illustrated a fossil fish that corresponds with the species Prionolepis cataphractus from Haqel. The first scientific presentation on the fossil fishes of Haqel was in 1703 at the French Academy of Sciences, and the first scientific studies were conducted by Henri Marie Ducrotay de Blainville in 1818. Lady Hester Stanhope collected and circulated fossil fishes from Haqel and Sahel Alma during the early 19th century, contributing to the study of these specimens by scientists such as Louis Agassiz. The Hadjoula site was only discovered in the late 19th century, and the Nammoura site in the early 20th century.

Paleobiota

Vertebrates

Jawless fish

Cartilaginous fish

Ray-finned fish

Lobe-finned fish

Amniotes

Invertebrates

Arthropods

Molluscs

Echinoderms

Annelids

Plants

See also

• List of pterosaur-bearing stratigraphic units
• Paleontology in Lebanon