Kasimovian (late Pennsylvanian) cornute rugose corals from Egypt: taxonomy, facies and palaeogeography of a cool-water fauna from northern Gondwana
Author
El-Desouky, Heba
Author
Herbig, Hans-Georg
Author
Kora, Mahmoud
text
Swiss Journal of Palaeontology
2023
32
2023-11-27
142
1
1
39
http://dx.doi.org/10.1186/s13358-023-00296-0
journal article
10.1186/s13358-023-00296-0
1664-2384
12003174
Bothrophyllum okense
Kossovaya, 2001
(
Fig. 13B
1–B
4
).
Material:
One preserved corallite (RAh 37), collected from the basal shales of lower member of the Aheimer Formation. Three transverse thin-sections are available.
Description:
External characters: The corallite is ca.
20 mm
in length. Calyx and apical end parts of are largely eroded. The external wall is partly damaged, eroded and enclosed in fossiliferous mud (
Fig. 13B
1
). The outer wall of the corallite in cross section is irregular.
Internal characters: The early preserved growth stage (
Fig. 13B
2
), in a diameter of
14 mm
there are 30 major septa.
All major
septa are long, some reach more than 2/3 of the corallite radius, leaving a small axial area which is filled with a diagenetically altered axial structure formed from the axial ends of the major septa and axial tabellae.
Septa
are strongly thickened in the tabularium, but thin in the very narrow dissepimentarium that consists of two rows of dissepiments. In the following higher section (
Fig. 13B
3
) cardinal and counter septa are long and meet in the corallite center forming an axial septum that contributes with other septal axial ends in making a loose axial structure. At this stage, there are 31 septa for about
14 mm
. In the higher mature thin-section near the eroded calice (
Fig. 13B
4
), all septa are broken due to the compaction of the calicular part. There are about 34 septa in 13.5 mm compressed diameter. The counter septum is still long and reach the corallite centre, in contrast to the cardinal septum that seems to be shorten (
Fig. 13B
4
). The axial structure that formed of the axial tabellae and inner ends of the longest major sept is still present. In a fairly good-preserved part of the corallite wall, a narrow dissepimentarium composed of 2 rows of simple concentric inter-septal dissepiments is present (
Fig. 13B
4
).
Cardinal
fossula is poorly developed. Minor septa are very short, confined to the dissepimentarium in the mature section (
Fig. 13B
4
), enter the tabularium as thick pegs.
Discussion:
The specimen shows greatest similarity to
Bothrophyllum okense
Kossovaya, 2001
from the Moscovian of the
Moscow
Basin in
Russia
, despite the incomplete preservation and the diagenetic alteration of the skeleton of the current species. It was compared with the Egyptian slightly older bothrophyllids (Rod EL Hamal Formation) and with other Moscovian and Kasimovian
Bothrophyllum
spp.
from the
type
region of the
Moscow
Basin have been discussed by Kora et al. (2019;
Table 1
).