Coral ? From Algeria (laghouat saharian Atlas moutains)

[derg]

Hello! i have found this rock laying on the surface of a dry saharian river. It is a dark blue hard limestone with some fossils in it.  This facies is known here as between upper oxfordian and lower Kimmerijian. I think it's a kind of coral. Is it really? i have put some "vaseline codex" on the rock to make it more bright. Sorry for my poor english.

Site: Laghouat, Algeria, north africa.

[Fossildude19]

Welcome to the Forum.  

 

Maybe these fellows can make a determination.

 

@TqB,  ... @FossilDAWG 

Regards,

[Al Dente]

It looks like a nice example of a Jurassic stromatoporoid. Cladocoropsis is a possibility.

[TqB]

I'm with Al Dente, it's not a coral. Nice fossil!

[derg]

Thanks , very helpful!

Did anyone tried to obtain  a thin rock slice  with i may say "a garage tools" ( not those expensive professionl ones)?

[FossilDAWG]

I agree, not a coral but a stromatoporoid is a good suggestion.  Sections would be nice, but the natural section in the photo you posted is quite good.

 

Don

[jpc]

Interesting.  I had to look up stromatoporoid

Laghouat... I was there a few times many many years ago... 1993.  

I did find some corals at Taghrit.

[derg]

a new photo! 

Edited February 16, 2017 by derg

[Wrangellian]

Interesting! I did think it looked spongish before I saw the comments that followed, but I had assumed that stromatoporoids were restricted to the Paleozoic.

Very nice finds.

[derg]

Yes! very strange fossils theses stromatoporoids!  but they were also  reef builders in the mesozoic  era, especially upper jurassic. Hard to study because they demand thin slices and a microscope, consuming time and money.

Here is more other samples of these fossils, same location; Laghouat, Algeria(DZ), North Africa.We can see two new fossils. Washed with water and a brush they look blurry . Wiped with some vaseline they look beautiful.

 

 

[derg]

A photo of the site of findings!

[TqB]

This one is a coral (you can see septa), possibly rugose. Could some of these be Palaeozoic?

 

[derg]

Thank you TqB! palaeozoic? no! the geologic map of this area doesn't show outcrop lower than oxfordian stage. It seem's then that corals and stromatoporoids were sharing the same "paleoecological conditions" i may say.

[TqB]

13 hours ago, derg said:

Thank you TqB! palaeozoic? no! the geologic map of this area doesn't show outcrop lower than oxfordian stage. It seem's then that corals and stromatoporoids were sharing the same "paleoecological conditions" i may say.

 

Thanks, maybe it's something like Thecosmilia but I don't know much about scleractinians!

 

You have an interesting assemblage there.

[Kosmoceras]

19 hours ago, TqB said:

This one is a coral (you can see septa), possibly rugose. Could some of these be Palaeozoic?

 

18 hours ago, derg said:

Thank you TqB! palaeozoic? no! the geologic map of this area doesn't show outcrop lower than oxfordian stage. It seem's then that corals and stromatoporoids were sharing the same "paleoecological conditions" i may say.

 

Is there a possibility that these are Palaeozoic rock clasts from a Mesozoic conglomerate?

[derg]

Kosmoceras: geologic map of these area shows that these rock clasts are quaternary conglomérates ( q 3-4 and q 5-6). All theses fossils were already mentioned  in their original outcrop ( mountain Lazreg)  as jurassic (upper oxfordian- lower kimmeridjian). No paleozoic (outcrop or rock clast) found in this area (Laghouat) since more than a century of geological studies. 

 

[derg]

My last finding! more likely a coral.

[abyssunder]

You might need this document for your corals and stromatoporoids: L. Beauvais and S. Nouiouat. 1993. Une nouvelle faune de coralliaire jurassiques dans l'Atlas sahariens d'Algerie [A new Jurassic coral fauna from the Saharan Atlas of Algeria]. Geobios 26(3):291-318

 

 

" This paper contains the description and figuration of fifteen Scleractinian species belonging to fourteen genera. Two species are new. The material comes from three outcrops of the Saharian Atlasis of Algeria. Five genera and one species of Calcisponge have been identified too. This fauna belongs to Late Jurassic, however, four species collected at the top of the Hassi M'Guita series, have been found up to day, exclusively in Middle Jurassic. "

 

Species described include Cladocoropsis memoria-naumanni (YABE).

 

1927 - Stromatopora memoria-naumanni YABE, p. 90.
1935 - Stromatopora (Parastromatopora) memoria-naumanni YABE in YABE & SUGIYAMA, p. 180, pl. 47-52, 55, 58, 62 et 63.
1982 - Cladocoropsis memoria-naumanni (YABE), Beauvais, p. 41, pl. 1, fig. 3.
1989 - Cladocoropsis memoria-naumanni (YABE), Beauvais, p. 273, pl. 60, fig. 3.

 

Repartition stratigraphique et geographique - Espece tres repandue dans le Jurassique superieur-Berriasien de tout le bassin tethysien (Japon, Philippines, Indondsie, Grace, Italie, Algerie).
Localite - Djebel Azreg.
Materiel - Une plaque mince (AZG 036).

 

 

[derg]

Thank you Abyssunder for this  precious document. The association of corals stromatoporoids ans chetaetids is common in upper jurassic  reefs of laghouat, Algeria.Here is other photos of stromatoporoids that sometimes  seem to show corals like structures in their body. Relation between corals and stromatoporoids is fascinating!