factors affecting the behavior and trait of some ...

Egypt. Jour. Paleontol., Vol. 10, 2010, p. 107-121

ISSN 1687 - 4986

FACTORS AFFECTING THE BEHAVIOR AND TRAIT OF SOME CENOMANIAN OYSTERS FROM SINAI, EGYPT Manal S. MEKAWY Geology Department, Faculty of Science, Suez Canal University, Ismailia, Egypt [email protected]

ABSTRACT Factors affecting the behavior and trait of oysters include water movement, salinity, oxygenation, temperature, food, sedimentation and others. In the present work, another factor that may affect the ecological community of oysters, namely predators. Predators play an important role in the distribution and abundance of species in ecological communities (Bambach and Kowalewski, 1999). In Egypt, among the oysters that dominate in the Cenomanian are Ceratostreon flabellatum (Goldfuss), Rhynchostreon suborbiculatum (Lamarck), Ilymatogyra africana (Lamarck), Ambigostrea pseudovillei Malchus, Rastellum carinatum (Lamarck) and Costagyra olisiponensis (Sharpe). They experienced complete disappearance in the Early Turonian. This study evaluates the role of predators in evolution and extinction of the Cenomanian oysters using three species of them; Ceratostreon flabellatum, Rhynchostreon suborbiculatum and Costagyra olisiponensis recorded from Gebel Yelleg, North Sinai, Egypt from trace fossils left on their skeletons.

Key words: Predators, Cenomanian oysters, Gebel Yelleg; North Sinai, Egypt

INTRODUCTION Extinction of oysters Most of the species of Cenomanian oysters, went extinct and completely disappeared in the early Turonian. The causes of their extinction remained unresolved and many hypotheses have been done to explain the oyster's death. Most of them have focused on global physical environmental changes such as overall cooling, changes in oceanic circulation patterns and ocean chemistry and general environmental degradation (Kauffman, 1984 & 1988; Kauffman et al., 1992; MacLeod, 1994; Fischer & Bottjer, 1995; MacLeod & Huber, 1996). Another hypothesis for this extinction may be the predators as biological factor. As noted by Vermeij (1982 & 1987), escalation, the evolutionary arms race, may be one of the most influential selective agents in the evolution of a group. This study explains the role of predators in the evolution and extinction of the Cenomanian oysters at Gebel Yelleg, North Sinai, Egypt. Predators of oysters The list of many enemies that prey on oysters includes flatworms, mollusks, echinoderms, crustaceans, fishes, birds and mammals. The most dangerous are those which prefer oyster meat to other types of food (Fig. 1). Carnivorous gastropods The deadliest enemies of oysters are various gastropods. Oyster drills are major predators of the oyster such as Urosalpinx cinerea and Eupleura caudate. Both are small snails, abundant in intertidal and shallow waters. They attack clam and oyster seed by drilling a small hole through the shell with slightly beveled or

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straight hole. Holes can be found practically any where on the oyster shell (Flimlin & Beal, 1993). Urosalpinx attacks oysters and other mollusks by drilling a round hole in the shell. The hole, usually made in the upper (right) valve of the oyster, tapers toward the inner surface. Starfish The starfish is also a highly destructive predator on oysters. The common species include Asterias forbesi and Asterias vulgaris. The starfish pulls the two shells or valves of an oyster bivalve apart with its five arms and inserts its stomach into the exposed shell cavity. As enzymes are released, the clam meat is digested and absorbed by the starfish (Flimlin & Beal, 1993). Flat worms The flat worm Stylochus ellipticus and Pseudostylochus ostreophagus are predators which attack adult and young oysters and frequently inflict serious damage to oyster populations. Flimlin & Beal (1993) stated that the worm slides between the valves of oysters; once inside it consumes the meat and the polychaete worm Polydora can damage or kill oysters producing numerous blisters at the base of the adductor muscle inside the shell, weakening the muscle to the point that the oyster can not completely close its valves.

Fig. 1. Representatives of the most dangerous Cretaccous marine invertebrate predators 1, Ammonoid; 2, Homarid lobster; 3, Belemnite; 4, Naticide gastropod and 5, brachyuran. Adapted from Walker and Brett (2002)

Factors affecting behavior and trait of Cenomanian oysters

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Crabs Ryder (1884) was the first to include the blue crab, Callinectes sapidus and the common rock crab, Cancer irroratus, in the list of oyster enemies. Other predators of oysters are the green crab, Carcinus maenas and the mud crabs, Dsypanopeus sayi and Panopeus herbstii. They open shell fish with their claws by crushing the entire clam, chipping a valve edge, or forcing the valves apart (Flimlin & Beal, 1993). Fish Another predator which feed on mollusks and occasionally causes extensive destruction of oysters is the fish. The fish uses its powerful pharyngeal teeth to crush the shells. Predators through geological time The data from the marine fossil record makes a strong case for the existence of predatory attack on shelled organisms as early as the latest Precambrian and early Cambrian (Brett & Walker, 2002) (Fig. 2). Following the end-Permian mass extinction, the data suggests episodic, but generally increasing, predation pressure on marine organisms through the Mesozoic-Cenozoic interval (Kowalewski & Kelley, 2002). Bambach & Kowalewski (1999) stated that the diversity of predators remained at a nearly constant proportion from the Late Triassic to mid-Cretaceous. During Late Cretaceous-Neogene, predators diversified faster than the rest of the fauna. According to Walker & Brett (2002) predation in benthic communities may have intensified substantially in the Late Cretaceous-Early Cenozoic with the evolution of negastropods, varied crustaceans, durophagous fish, large-predator guilds were filled predominantly by varied marine reptiles; whereas neoselachian sharks, teleosts, and marine mammals dominated in similar roles throughout the Late Cretaceous to Cenozoic. Walker & Brett (2002) mentioned that the Early Cretaceous marked the beginnings of a major reorganization of marine predators, including the rise of neogastropods, numerous cephalopod predators, and several new vertebrate predatory guilds.

Fig. 2. The first appearances and diversification of major marine molluscivores. Adapted from vermeij (1987) and Carter et al. (1998).

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Predators play an important role in the distribution and abundance of species in ecological communities. The fossil record offers us diverse and provocative evidence of predator-prey interactions through time; ranging from predation traces to functional morphology and phylogenetic affinities (Kowalewski & Kelley, 2002). Kowalewski (2002), mentioned that there are various direct and indirect indicators of predation available to paleontologists, including trace fossils, coprolites, gut contents, exceptional preservational events, taphonomic patterns, and indirect evidence provided by functional morphology and phylogenetic affinities. Stratigraphic setting The Cenomanian oysters of Gebel Yelleg, North Sinai, Egypt were selected as a case study to explain the hypothesis. G.Yelleg is located between 30º 15´- 30º 35´ N and 33º 15´- 33º 47´ E (Fig. 3a). There, the Galala Formation (Cenomanian) overlies the Lower Cretaceous Malha Formation and conformably underlies the Turonian Wata Formation. It measures about 422 m and is composed mainly of dolostone, dolomitic limestone, and argillaceous limestone intercalated with marl and shale (Mekawy, 2007) (Fig. 3b).

MATERIAL AND METHODS A total number of 480 specimens of Ceratostreon flabellatum, 388 specimens of Rhynchostreon suborbiculatum and 32 specimens Costagyra olisiponensis are collected from the Cenomanian rocks (Galala Formation) of Gebel Yelleg. The accumulations are photographed and their general characteristics are noted. In the laboratory, the studied specimens are washed carefully with water and then dried. Afterward the interiors of left oyster valves are examined and the location of the predator's action is determined in the attacked specimens. Representative free specimens of the interiors of left oyster valves are photographed with digital camera and then displayed in plate (1). All specimens are housed in the Geology Department, Suez Canal University, Ismailia, Egypt and are numbered with abbreviations GY for Gebel Yelleg.

RESULTS The Cenomanian rocks of Gebel Yelleg are highly fossiliferous with bivalves, gastropods, echinoids and ammonites. Oyster shells are abundant especially Ceratostreon flabellatum (Goldfuss, 1833), Rhynchostreon suborbiculatum (Lamarck, 1801) and Costagyra olisiponensis (Sharpe, 1850) that collected from the marl or the carbonate sequence. They are found as well preserved shells (Mekawy, 2007). In the field flabellatum and suborbiculatum shells are recorded in three levels whereas olisiponensis shells are accumulated in one level (Fig. 3b). So, the studied oysters are divided into two groups; flabellatum and suborbiculatum group and olisiponensis group. The main field observations of both groups are summarized in Table 1.

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Bed Lithology N o.

33°

Halal *

Suez

23

31°

El-Hamra *

SINAI

30°

Themed

22 * Nezzazat Ekma

50 km

Ras Mohamed

studied section

(A)

90 m

13

60 m

12 L2 10 9

30 m

7

0

Ob L3 L2 L1

Olisiponensis bed Level 3 Level 2 Level 1

6

Lower

29°

28°

14

8

EZ SU OF LF GU

21 20 19 L3 17 16 15

Middle

N

Yelleg * El-Minsherah

OF AQ ABA

Upper

25 Ob

Cenomaian

35°

MEDITERRANEAN SEA

GULF

Stage

5

Marl

4

Shale Sandy limestone

3

Argillaceous Limestone

L1

Dolomitic limestone

1

Limestone

Aptain (B)

Fig. 3. a. Location map of the studied area; b. Stratigraphic columnar section of the Cenomanian rocks at Gebel Yelleg, North Sinai, Egypt.

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MEKAWY Table 1. The principle field observations of the studied oysters. Age

Packing

size

Abundance

Predation trace

Costagyra olisiponensis

Late Cenomanian

Highly dense

Very large

Abundant

Very low-zero

Large

Common-rare

Very high

Medium

Abundantcommon

High

Ceratostreon flabellatum & Rhynchostreon suborbiculatum

Faunal species

Level 3 Level 2

Level 1

late Middle Cenomanian

early Middle Cenomanian

Early Cenomanian

Loose (scattered randomly on the marl bed) Loose (scattered randomly on the marl bed) Dense (very compact bed form within limestone)

Small

Abundant

Very low-zero

Flabellatum and suborbiculatum shells group The associated fauna with this group are the bivalves Nucula (N.) margaritifera Douvillé 1916, Barbatia aegyptiaca (Fourtau, 1917), Granocardium productum (Sowerby, 1832), Tenea delettrei (Coquand, 1862) and Maghrebella forgemoli (Coquand, 1862). The gastropods are Pterocera incerta ďOrbigny, 1842, Harpagodes heberti (Thomas & Peron, 1889), Colombellina (C.) Fusiformis Douvillé, 1916 and Pterodonta deffisi Thomas & Peron, 1889. The echinoids include Tetragramma variolare (Brongniart, 1822), Coenholectypus excisus (Desor, 1847) and Hemiaster (H.) gabrielis Peron & Gauthier, 1878. Level no.1 This is the lowest level recognized in the present study. Flabellatum and suborbiculatum shells are small sized, compact, densely packed, dominantly articulated and randomly oriented within carbonate rocks. No predation trace is recorded except few specimens (Figs. 4-7). Level no.2 The manner of accumulation of the oyster shells in this level is completely different from Level 1 where most of them are disarticulated, convex-down oriented, moderately sorted, medium sized and scattered randomly on the marl bed with a decrease in number of shells. The predation traces concentrated on the umbo, muscles and periphery of the inner surface of the oyster's left valves (Figs. 4-7). Level no.3 The field observations of oyster shells in this level show a great similarity to Level 2 with increase in size, predation trace and decrease in number (Figs. 4-7).

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Fig. 4. a, c & e. Photographs showing the size of flabellatum shells in the three levels recorded in the Galala Formation (Cenomanian) of Gebel Yelleg, North Sinai, Egypt b, d & f. Field photographs showing the flabellatum shells in the three levels (Photograph no. d from Pl. 1, Fig. 1 in Mekawy, 2007).

80% 70% 130= 9%

60% level 1

50%

1000= 67%

level 2

40%

level 1

350= 24% level 2

level 3 level 3

30% 20% 10% 0% 1

(a)

(b)

Fig. 5: a. Distribution of the attacked samples of the studied flabellatum shells in the three levels. b. The abundance of the studied flabellatum shells in the three levels recorded from the Cenomanian rocks of Gebel Yelleg.

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Fig. 6: a, c & d. Photographs showing the size of suborbiculatum shells in the three levels recorded in the Galala Formation (Cenomanian) of Gebel Yelleg., North Sinai, Egypt. b. Field photograph of suborbiculatum shells (from P1. 1, Fig. 3 in Mekawy, 2007). E. Accumulations of suborbiculatum shells.

60%

98=7%

50%

290=21%

40%

level 1

level 1 1000=72% level 2

level 2

30%

level 3

level 3

20% 10% 0% 1

(a)

(b)

Fig. 7: a. Distribution of the attacked samples of the studied suborbiculatum shells in the three levels. b. The abundance of the studied suborbiculatum shells in the three levels recorded from the Cenomanian rocks of Gebel Yelleg.

Costagyra olisiponensis shells group Costagyra olisiponensis shells are accumulated within a limestone bed with a large sized, very thick shell, densely packed, randomly oriented and moderately disarticulated. Nearly no predation traces are noted (Fig. 8).


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Fig. 8. a & d. Large and robust olisiponensis shells recorded in the Galal Formation (late Cenomanian) of Gebel Yelleg, North Sinai, Egypt. b & c. Field photographs showing olisiponenisis bed (Photograph c from Pl. 1, Fig. 4 in Mekawy, 2007).

DISCUSSION In this study, the data provides a lot of information about the ecological community of the Cenomanian age of Gebel Yellg, North Sinai, Egypt from the trace fossils left on their skeletons. This information allows several important conclusions to be drawn. In the first group of studied oysters (flabellatum and suborbiculatum shells, level 1) (early Cenomanian), their accumulation with the small size and absence of the predation traces may suggest the presence of big-sized predators that prefer attacking medium-and big-size preys. Also the dense packing of the oyster shells in this level may be a way of defending and protecting themselves against the predators. According to Palmer (1982) who postulated that the increase in shelly epifauna in hardground communities during the Mesozoic may be due to predation rather than to scour resistance. Ozanne & Harries (2002) mentioned that by the Late Cretaceous, the inoceramids had evolved two main anti-predatory strategies; avoidance and resistance. Stanley (1968, 1977) recognized that many characteristics in the mollusks were a result of competitive selective pressures imposed by predatory organisms, like preexisting or newly evolved adaptations in bivalves. They include a wide variety of traits such as escape behaviors, thicker shells and perhaps most important characteristics enabling bivalves to colonize infaunal habitats out of the reach of surface-dwelling predators. Vermeij (1977,

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1987) stated that the cementation in bivalves is a post-Paleozoic habit; it appears that the Late Triassic and Jurassic were key times in the evolution of this habit and this pattern is strikingly coincidental with the first appearance of many durivorous predator groups during the Mesozoic and their diversification thereafter. In levels 2 & 3 in the same group (middle Cenomanian), the oyster shells display random state on the marl bed accompanied by the increase in size, decline in number and increase on the predation traces (Figs. 4 & 6). The oyster shells display two main types of predation traces; bore holes and deformation marks. The bore holes concentrate on umbo, muscle and the periphery area (the places control the opening and closing the shell) of the inner surface of the left valves (where the right valves nearly vanished) (Pl. 1, Figs. 1, 2, 4 ,7, 8, 10, 12, 13, 14, 15, 16). Primarily responsible for this bores are carnivores gastropods such as Colombellina (Colombellina) fusiformis Douvillé, 1916; Pterodonta deffisi Thomas & Poron, 1889; Ampullina (Ampullina) quaasi (Maxia, 1941); Tylostoma (Tylostoma) pallaryi (Peron & Fourtau, 1904) (El Qot, 2006, p. 104, 105, 106, 109). The shapes of bores may be rounded, conical and cylindrical (Pl. 1, Figs. 2, 4, 5, 12, 13, 14, 15, 16). El- Shazly, (2007) stated that the gastropods drill rounded holes in the shell or slightly conical approaching cylindrical and perpendicular on the shell surface. Gastropods utilize their radula accompanied, in most cases, with the secretion of a chemical to drill a hole in the valve to gain access to the bivalve's viscera (Ozanne & Harries, 2002; El-Shazly, 2007). Explanation of Plate 1 Fig. 1: Left valve's inner surface of flabellatum shell show signs of drilling on the periphery and deformation marks of crustacean, middle Cenomanian, Galala Formation, Gebel Yelleg. Fig. 2: Numerous bores concentrated on the umbonal area of left valve's inner surface of suborbiculatum shell and crustacean attack on the periphery, middle Cenomanian, Galala Formation, Gebel Yelleg. Fig. 3: Predation traces on the periphery of left valve's inner surface of suborbiculatum shell may made by crustacean or starfish, middle Cenomanian, Galala Formation, Gebel Yelleg. Figs. 4 & 15: Different bores concentrated on the umbonal area and periphery of left valve's inner surface of flabellatum shells . In addition to crustacean attack on the outer margin of the same shells, middle Cenomanian, Galala Formation, Gebel Yelleg. Figs. 5 & 13: One rounded bore near the adductor muscle of left valve's inner surface of flabellatum shell, middle Cenomanian, Galala Formation, Gebel Yelleg. Figs. 6, 7 & 9: Deformation marks on the outer margin of left valve's inner surface of suborbiculatum shells may made by crustacean or starfish, middle Cenomanian, Galala Formation, Gebel Yelleg. Fig. 8: Predation traces on the outer margin of left valve's inner surface of flabellatum shell may made by crustacean or fishes, middle Cenomanian, Galala Formation, Gebel Yelleg. Fig. 10: Attack traces on umbonal area and periphery of left valve's inner surface of suborbiculatum shell may made by gastropods, crustacean or starfish, middle Cenomanian, Galala Formation, Gebel Yelleg. Fig. 11: Polychaetes are encrusted on the outer surface of left valve of suborbiculatum shell, middle Cenomanian, Galala Formation, Gebel Yelleg. Fig. 12: Five rounded bores in the adductor muscle of left valve's inner surface of suborbiculatum shell , in addition to polychaete near the bores, middle Cenomanian,Galala Formation, Gebel Yelleg. Fig. 14: One big rounded bore in the umbonal area of left valve's inner surface of flabellatum shell , in addition to polychaete near the bores, middle Cenomanian,Galala Formation, Gebel Yelleg. Fig. 16: One rounded bore near the adductor muscle of left valve's inner surface of suborbiculatum shell , middle Cenomanian, Galala Formation, Gebel Yelleg.


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PLATE 1

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Another predator is the decapod crustaceans, such as crabs and clawed lobsters which are responsible for deformation marks. Most molluscivorous crabs posses a large master claw that both shears and crushes as it closes on the margin of the valves, and a smaller cutter claw, used to tear away flesh, to hold or to manipulate prey (Ozanne & Harries, 2002). El-Shazly (2007) mentioned that crab predators cause shell injuries breaking, peeling, crushing the shell or even swallow the whole prey. In the present study (Pl. 1, Figs. 1, 4, 6, 8, 9, 10, 15) show signs of deformity may be for the crabs. The present writer found no fossils of crabs or lobsters in the study area, it is rare but the previous works recoded it. Unlike the mollusks, the exoskeleton of crabs and lobsters is made of a chitinous material that is susceptible to rapid bacterial decomposition, and their record is taphonomically biased (Plotnick et al. 1988; Allison 1990) in Ozanne & Harries (2002). Flatworms (polychaete) are dangerous predators and common in the study area (Pl. 1, Fig. 11). It is a flattened, pale, and cream-colored with 25 mm or less in length. It slides between the valves of the oysters and consumes the soft parts (Pl. 1, Fig. 12). They almost leave behind them a hollow, U-shaped tube observed within the oyster shell. Starfish is another deadly predator of oysters. It arched over the clam, holding the gap upward against its mouth while applying its arm and tube feet to the slides of the valve and slightly opens it, and secretes digestive enzymes onto the soft parts of the clam and digesting it in its own shell (El-Shazly, 2007). Their predation traces are shown (Pl. 1, Figs. 2, 3, 6, 7, 10, 16). Molluscivory is common among modern fishes, and many studies have shown that sharks and rays are efficient predators of epifaunal and shallow infaunal bivalve communities (Ozanne & Harries, 2002). Flaking and chipping margin of the right valve of Cubitostrea is an evidence of fish predation (El-Shazly, 2007). The following image may show some of this predation traces (Pl. 1, Fig.8). The author's hypothesis that the predation traces especially the bores in levels 2 & 3 which focused on certain areas such as the umbo, muscle and the periphery area of the inner surface of the left valve, may support the idea that the predators have became stronger, more diversity and more chance to attack the oysters which begins its offensive from the right valve of the oysters because it is thinner and more exposed than the left one. This assumption may be one reason for the absence of the right valves, as the predators destroyed them to get their food (soft parts). Also the change in the oyster's traits (increase in size and decline in number) that differ from level 1 may be due to the competitive pressures between them and the predators. Vermeij (1987) hypothesized that adaptations and behaviors within certain invertebrate groups, such as bivalve and gastropod mollusks, may in part have been driven by escalating predator-prey interactions. Bambach (2002) noted that the predator diversity would increase in the face of decreasing biomass (abundance) of prey. McGinley et al. (2007) stated that increasing the population size of prey will result in a corresponding increase in the population size of the predator because the predator has more food. Similarly, prey populations are expected to decline as the population size of a predator increases


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because of increases of increased predation pressure. Bambach (2002) documented that predators could increase their proportional share of total diversity by specializing on fewer prey taxa. Kowalwski (2002) noted that biotic traces made by predators or parasites are often non-random in their distribution on prey skeletons and drill holes made by snails may concentrate in a particular area of the shell. In the second group of studied oysters (olisiponensis shells, late Cenomanian); the predation traces are nearly absent and the olisiponensis shells experienced an abnormal size and robust with dense packing form. The author's interpretation of these observations is that the change in oyster's traits is a way to protect themselves against predators and the predators may be exacerbated in the end of the Cenomanian of Gebel Yellg and may be one of the reasons of the extinction of Cenomanian oysters. Gunter (1955) indicated that the natural mortality rates for oysters in estuaries were about 2-18% whereas mortality rates for oysters in estuaries when predators were present was about 8-90%. Walker & Brett (2002) documented that grypheid and exogyrid oysters, remained common on Mesozoic soft substrates but these organisms were partially hidden and evolved thick and robust shells. Ozanne & Harries (2002) stated that the evolutionary innovations of the inoceramid for resistance to predators are thickening of the shell, increasing convexity of the valves or presence of deterrent ornamentation.

CONCLUSIONS 1- The predators are an important biological factor affect the ecological community of oysters. 2- The predation traces left on the oyster's skeleton in the Cenomanian rocks of Gebel Yelleg display two main types; bore holes and deformation marks. 3- Of the most dangerous predators in the present study are carnivores gastropods; decapod crustaceans such as crabs and clawed lobsters; flatworms; starfish and fishes. 4- The predation pressure on the Cenomanian oysters in Gebel Yelleg increase upwards. 5- As a result of increasing the predation pressure upwards the abundance of the Cenomanian oysters decreased while their size increased. 6- The abnormal thickness of the robust shells of Costagyra olisiponensis (late Cenomanian) is a way of self-defense against predation. 7- The organisms may change their traits and behaviors as a way of defending themselves against their enemies. 8- Both predator and prey are in a continuous evolutionary state in their predation relationship. 9- The predators may be spread seriously at the end of Cenomanian. The predators may be one of the reasons responsible for the extinction of the Cenomanian oysters at Gebel Yellg.

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ACKNOWLEDGEMENTS I express my sincere appreciation to Prof. Dr. Mahmoud M. Kora, Geology Department, Mansoura University and Prof. Dr. Gouda I. Abdel-Gawad, Geology Department, Beni Suef University for critical review of the manuscript. I would like to express my deepest gratitude to Prof. Dr. Abdel Galil Hewaidy, Geology Department, Al-Azhar University for useful comments, fruitful discussions and continuous encouragement.

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Kowalewski, M., 2002. The fossil record of predation: An overview of analytical methods. Paleontological Society Papers, 8: 3-42. Kowalewski, M. and Kelley, P. H., (eds.) 2002. The fossil record of predation. Paleontological Society Papers, 8: 395-398. Kowalewski, M., Dulai, A. and Fürsich, F. T., 1998. The fossil record full of holes: The Phanerozoic history of drilling predation. Geology, 26: 1091-1094. MacLeod, K. G., 1994. Extinction of inoceramid bivalves in Maastrichtian strata of the Bay of Biscay region France and Spain. Journal of Paleontology, 68: 1048-1066. MacLeod, K. G. and Huber, B. T., 1996. Reorganization of deep ocean circulation accompanying a Late Cretaceous extinction event. Nature, 380: 422-425. McGinly, M., Duffy, J. E. and Judith, S. W., 2007. "Predation". Encyclopedia of Earth. Mekawy, M. S., 2007. Taphonomy of Cenomanian oysters from Gebel Yelleg, North Sinai, Egypt. Journal of Paleontology, 7: 335-348. Ozanne, C. R. and Harries, P. J., 2002. Role of predation and parasitism in the extinction of the inoceramid bivalves: An evaluation . Lethaia, 35: 1-19. Palmer, T. J., 1982. Cambrian to Cretaceous changes in hardground communities. Lethaia, 15: 309-323. Ryder, J. A., 1884. A contribution to the life-history of the oyster (Ostrea virginica, Gmelin, and O. edulis, Linn.). In George Brown Goode, The fisheries and fishery industries of the United States. Section I, Natural history of useful aquatic animals, pp. 711-758. Stanley, S. M., 1968. Post-Paleozoic adaptive radiation of infaunal bivalve mollusks-A consequence of mantle fusion and siphon formation. Journal of Paleontology, 42: 214-229. Stanley, S. M., 1977. Trends, rates, and patterns of evolution in the bivalvia. Elsevier, 214-229. Vermeij, G. J., 1977. The Mesozoic marine revolution: Evidence from snails, predators and grazers. Paleobiology, 3: 245-258. Vermeij, G. J., 1982. Unsuccessful predation and evolution. American Naturalist, 120: 701-720. Vermeij, G. J., 1987. Evolution and Escalation: An Ecological History of Life. 527 pp. Princeton University Press, Princeton, NJ. Walker, S. E. and Brett, C. E., 2002. Post-Paleozoic patterns in marine predation: Was there a Mesozoic and Cenozoic marine predatory revolution? Paleontological Society Papers, 8: 119-194.