On a Palaeoxyris shark egg capsule from the Middle ...

On a Palaeoxyris shark egg capsule from the Middle Permian of Jordan 1

1

2

Jan Fischer , Sebastian Voigt , Abdalla Abu Hamad , 3 4 4 Hans Kerp , Jörg W. Schneider & Frank Scholze

Pedicle structure through time

Introduction

66.0

?

P. sp. CROOKALL 1930

100.5

P. sp. VULLO 2013

Syria

Amman

Ma‘in Formation

Jerusalem

[m]

3

Triassic Permian

Saudi Arabia

Jordan

2 Umm Irna Formation

The probably hybodontiform produced fossil chondrichthyan egg capsule morphotype Palaeoxyris BRONGNIART, 1828 comprises 26 species[1] with fossils coming from predominantly freshwater to brackish deposits[2]. The known stratigraphic record of Palaeoxyris spans about 240 million years from the Early Carboniferous (Viséan)[3] to the Late Cretaceous [4] (Turonian) . Remarkably, Palaeoxyris has never been reported from Permian strata[5,6]. A recent find of Palaeoxyris from nearshore alluvial plain deposits of the late Middle Permian (Capitanian) Umm Irna Formation of central Jordan[7] indicates that this perceived stratigraphic gap was a result of collection failure.

Umm Irna Fm.

Dead Sea

1

0 m sf sm

UGKU locality

fine-/middlegrained sandstone fine-grained sandstone

intraformational pebbles

N

mudstone

plant remains

0 km 5

trough crossbedding

Palaeoxyris

root traces

Specimen UGKU 1978 The Jordanian Palaeoxyris specimen (UGKU 1978) is a single compressed body fragment lacking the beak and pedicle. Its taxonomic assignment is justified by the typical transverse rhomboidal pattern of the body, which is thought to be a result of the compression and superimposition of originally helicoidal twisted bands[1]. The discussed specimen is about 17 mm long and 9 mm wide preserving nine segments of at least six bands. Each band is 2 mm wide on average. The band pattern and band width of the Jordanian specimen is similar to various Paleozoic and Mesozoic Palaeoxyris[7]. Detailed comparison and species level identification, however, requires knowledge of certain morphologic traits of the pedicle. Paleozoic species show a rhomboidal ribbing structure that continues on the pedicle, whereas in Mesozoic species the rhomboidal ribbing structure of the body turns distally into parallel running bands[6]. Whether the Palaeoxyris from Jordan has Paleozoic or Mesozoic affinity with respect to the pedicle remains an open question due to imperfect preservation.

P. sp. SAUVAGE 1905

145.0

PostP. jugleri ETTINGSHAUSEN 1852

163.5

Permian parallel ribbing structure of the pedicle

174.1

?

specimen UGKU 1978

P. sino-coreanum SZE 1954

201.3

P. muensteri PRESL 1838

? P. alterna FISCHER et al. 2011

237.0

5 4

Nursery environment

P. friessi BÖTTCHER 2010

247.2 P. regularis BRONGNIART 1828

252.2

The Jordanian shark egg capsule was found in crevasse splay deposits intercalated with trough cross-bedded sandstones of low-sinuosity channels[7]. The paleoenvironmental interpretation supports the hypothesis that certain Paleozoic sharks preferred low salinity aquatic habitats for spawning. This strategy likely lowered offspring mortality rates as can be seen by its use in several extant sharks[8,9].

259.8

272.3

3 2 1 0 mm

crevasse splay (supposed deposition of Palaeoxyris)

perceived „Permian Gap“

sedimentary source area

oxidized floodplain

abandoned channel interfluve sediments low-sinuosity channel

point bar

peaty mire

298.9

References [1] - FISCHER, J., LICHT, M., SCHNEIDER, J. W., KRIWET, J. & KOGAN, I. (2014): Chondrichthyan egg capsule card, 2 pp. (DOI:10.13140/2.1.2322.5922).

323.2 P. helicteroides MORRIS 1840

P. carbonaria SCHIMPER 1850

P. warei CROOKALL 1928

[2] - CROOKALL, R. (1932): The nature and affinities of Palaeoxyris, etc. - Summary of Progress of the Geological Survey of Great Britain and the Museum of Practical Geology for 1931 part II: 122–140.

Pre-

0

[3] - SCHNEIDER, J. W., HOTH, K., GAITZSCH, B., BERGER, H. J., STEINBORN, H., WALTER, H. &ZEIDLER, M. K. (2005): Carboniferous stratigraphy and development of the Erzgebirge Basin, East Germany. - Zeitschrift der Deutschen Gesellschaft für Geowissenschaften 156: 431–466.

Permian

[4] - VIALOV, O. S. (1984): Nowaja nachodka jaizewych kapsul elasmobranchij Palaeoxyris; pp. 99–103 - in VIALOV, O. S., GAWRILISCHIN, W. I., DIDIKOVSKI, W. J., SOSIMOVITSCH, W. J., MAKRIDIN, W. P., MASLUN, N. W. & EYNOR, O. L. (eds.): Paleontologija i stratigrafija fanerosoja Ukrainy. Naukova dumka, Kiev. 0

[5] - SCHNEIDER, J. W. & REICHEL, W. (1989): Chondrichthyer-Eikapseln aus dem Rotliegenden (Unterperm) Mitteleuropas Schlussfolgerungen zur Paläobiologie paläozoischer Süßwasserhaie. - Freiberger Forschungshefte C 436: 58–69. [6] - FISCHER, J., SCHNEIDER, J. W. & BUCHWITZ, M. (2008): Pedicle ribbing structure of the egg capsule Palaeoxyris reflects a Palaeozoic to Mesozoic change-over in its chondrichthyan producers. - 78. Jahrestagung der Paläontologischen Gesellschaft, 8.10.09.2008, Erlangen, Erlanger Geologische Abhandlungen, Sonderband 6: 85–86. [7] - ABU HAMAD, A., FISCHER, J., VOIGT, S., KERP, H., SCHNEIDER, J. W. & SCHOLZE, F. (in press): First Permian occurrence of the shark egg capsule morphotype Palaleoxyris BRONGNIART, 1828. [8] - CONRATH, C. L. & MUSICK, J. A. (2010): Residency, space use and movement patterns of juvenile sandbar sharks (Carcharhinus plumbeus) within a Virginia summer nursery area. - Marine and Freshwater Research 61: 223–235. 0

P. sp. SCHNEIDER et al. 2005

358.9

1 2

P. lewisi ZIDEK 1976

[9] - HEUPEL, M. R. & SIMPFENDORFER, C. A. (2011): Estuarine nursery areas provide a low-mortality environment for young bull sharks Carcharhinus leucas. - Marine Ecology Progress Series 433: 237–244.

P. prendeli LESQUEREUX 1870

capsules are not to scale

Urweltmuseum GEOSKOP, Burg Lichtenberg (Pfalz), 66871 Thallichtenberg, Germany The University of Jordan, 11942 Amman, Jordan

spiral ribbing structure of the pedicle 3 4

Westfälische Wilhelms-Universität, 48149 Münster, Germany TU Bergakademie Freiberg, 09596 Freiberg, Germany/ Kazan Federal University, Russia