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Bregmaceros albyi , anatomy

Bregmaceros albyi , anatomy

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Bregmaceros albyi , anatomy

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  1. Bregmaceros albyi,anatomy Bregmacerotids are small fishes of the order Gadiformes, which attain a maximum length of about 10cm, and occur widely from coastal to mid-oceans waters in temperate and mainly in tropical seas (D’Ancona and Cavinato, 1965). The single genus family Bregmacerotidae is composed only of the genus Bregmaceros Thompson, 1840 with 13 valid species (Froese and Pauly, 2006). Thirty individuals of this species have been collected from Prassas 1 and show a total length range between 42-71 mm. Maximum body height equals the 17.8-15% of the standard length but fits 0.8-1 times into the head length. Similarly, the length of the head is the 17.6-18.6% of the standard length. Orbital diameter covers the 41.6-52.6% of head length. Usually, the jaw was clear and sometimes rounded, small teeth were evident. Twenty one individuals of this species have been collected from Prassas 2, having a total length range of 47-67 mm. The maximum body height is the 17.6-14.7% of the standard length but fits 0.8-1.1 times into the head length. The head is the 14.2-17.4% of the standard length. Orbital diameter is the 41.6-40.9% of the head length. Figure 5. Bregmaceros albyi Sixth International Symposium on Eastern Mediterranean Geology - April 2-5, 2007 Amman-Jordan The Pliocene Fish Fauna from Prassas, Crete Island, GreeceA. Agathaggelou*, C. Doxa, G. Iliopoulos, K. Panagioti, C.Fassoulas Natural History Museum of Crete, University of Crete *bio839@edu.biology.uoc.gr Bregmaceros albyi,anatomy Bregmacerotids are small fishes of the order Gadiformes, which attain a maximum length of about 10cm, and occur widely from coastal to mid-oceans waters in temperate and mainly in tropical seas (D’Ancona and Cavinato, 1965). The single genus family Bregmacerotidae is composed only of the genus Bregmaceros Thompson, 1840 with 13 valid species (Froese and Pauly, 2006). Bregmaceros albyi,anatomy Bregmacerotids are small fishes of the order Gadiformes, which attain a maximum length of about 10cm, and occur widely from coastal to mid-ocean waters in temperate and mainly in tropical seas (D’Ancona and Cavinato, 1965). Today, the single genus family Bregmacerotidae is composed only of the genus Bregmaceros Thompson, 1840 with 13 valid species (Froese and Pauly, 2006). Thirty individuals of this species have been collected from Prassas 1 and show a total Thirty individuals of this species have been collected from Prassas 1 and show a total length range between 42-71 mm. Maximum body height equals the 17.8-15% of the standard length but fits 0.8-1 times into the head length. length range between 42-71 mm. Maximum body height equals the 17.8-15% of the standard length but fits 0.8-1 times into the head length. Similarly, the length of the head is the 17.6-18.6% of the standard length. Orbital diameter covers Similarly, the length of the head is the 17.6-18.6% of the standard length. Orbital diameter covers the 41.6-52.6% of head length. Usually, the jaw was clear and sometimes rounded, small teeth were evident. Twenty one individuals of this species have been collected from Prassas 2, having a total length range of 47-67 mm. The maximum body height is the 17.6-14.7% of the standard length but fits 0.8-1.1 times into the head length. The head is the 14.2-17.4% of the standard length. Orbital diameter is the 41.6-40.9% of the head length. 1 cm Figure 4. Bregmaceros albyi 1 meter the 41.6-52.6% of the head length. Usually, the jaw is clearly distinct and sometimes rounded, small teeth are evident. Twenty one individuals of this species have been collected from Prassas 2, having a total length range of 47-67 mm. The maximum body height is the 17.6-14.7% of the standard length but fits 0.8-1.1 times into the head length. The head length is the 14.2-17.4% of the standard length. Orbital diameter is the 41.6-40.9% of the head length. ---------------------------------------------------------------- Figure 1. Map of Crete with the localities studied at Prassas. ------------------------------------------------------------------------------------------------------------------------------------------------ Introduction During the last year systematic excavations conducted at two different localities (Prassas 1, Prassas 2) found on the northwest and southeast of Prassas village (central Crete, Greece) (Figure 1.), revealed the existence of a Late Pliocene fish fauna. The studied specimens were found in diatomites dated between 2.6 and 2.1 Ma (Gaudant et al., 1994). The aims of this study are: • Introduction • During the last year systematic excavations conducted at two different localities (Prassas 1, Prassas 2) (Figure 1.) found on the northwest and southeast of Prassas village (central Crete, Greece) respectively, revealed the existence of a Late Pliocene fish fauna. The studied specimens were found in diatomites dated between 2.6 and 2.1 Ma (Gaudant et al., 1994). The aims of this study are: • Description of the fish fauna • Description of Bregmaceros albyi basic anatomy • Basic elements of Prassas paleoecology --------------------------- A Diatomites Marls 1 meter --------------------------------------------------------------------------------------------------------- • Description of the fish fauna • Description of Bregmaceros albyi basic anatomy • Basic elements of Prassas paleoecology --------------------------- B Diatomites Marls Figure 2. A: Stratigraphy and macrofauna of Prassas 1. B: Stratigraphy and macrofauna of Prassas 2 1 cm Fish Fauna The fauna consists of five different Teleost taxa. Bregmaceros albyi (Sauvage, 1880) (Figure 4.) seems to be the most abundant species. Spratelloides gracilis (Temminck & Schlegel, 1846) (Figure 3A.), Ilisha elongata (Bennett, 1830) (Figure 3B), Boops boops (Linnaeus, 1758) (Figure 3C.) and specimens that belong to the order Clupeiformes were also present. From the localityPrassas 1 (Figure 2A.) 132 specimens were collected of which 97 were identifiable (Table 1). From the locality Prassas 2 (Figure 2B) 157 specimens were collected of which 111 were identifiable (Table 1). Forty eight to fifty two vertebrae are present. The dorsal fin can be separated into three portions. The anal fin is composed of three portions and is inserted between the 14 and the 15 vertebrae. Pectoral fins are narrow (consisting of 13-15 rays). Pelvic fins consist of six, strongly elongate outer rays, which extend approximately up to the middle portion of the anal fin. Also, it is clear that the caudal fin is composed of 30 to 32 rays. The scales that covered the body are cycloid and small. A 1 cm A Table 2. Number of rays in dorsal and anal fins of Bregmaceros albyi B C 1 cm 1 cm • Conclusions • Bregmaceros albyi seems to be the most abundant species in the region of Prassas. • The Late Pliocene species identified in Prassas represent neritic species found today in tropical regions. • This correlation is indicative of a rather shallow sea environment, which was relatively close to the sea shore and did not directly communicate with the deep open sea, as indicated by the absence of meso- and bathy-pelagic fish species. • The existence of tropical species (like Bregmaceros), which are not found in the Mediterranean today, indicates that during the Late Pliocene the climate in the Eastern Mediterranean was clearly warmer. • Conclusions • Bregmaceros albyi seems to be the most abundant species in the region of Prassas. • The Late Pliocene species identified in Prassas represent neritic species found today in tropical regions. • This correlation is indicative of a rather shallow sea environment, which was relatively close to the sea shore and did not directly communicate with the deep open sea, as indicated by the absence of meso- and bathy-pelagic fish species. • The existence of tropical species (like Bregmaceros), which are not found in the Mediterranean today, indicates that during the Late Pliocene the climate in the Eastern Mediterranean was clearly warmer. Figure 3. A: Spratelloides gracilis. B: Ilisha elongata. C: Boops boops A/a Bregmaceros albyi Spratelloides gracilis Ilisha elongata Boops boops Clupeiformes Bibliografy U. D’Ancona, G. Cavinato, (1965) The fishes of the family Bregmacerotidae,Dana Report 64 1–92. Froese, R., Pauly, D., (2006): Editors. FishBase.World Wide Web electronic publication. http://www.fishbase.org, version(03/2006). Table 1. Average percentage of each species found in Prassas 1 and Prassas 2 Prassas 1 60% 5.7% 2.8% 2.8% 25.7% • Bibliography • Froese, R., & Pauly, D. (2006): Editors. FishBase. World Wide Web electronic publication. http://www.fishbase.org, version(03/2006). • D’Ancona, U., & Cavinato, G. (1965): The fishes of the family Bregmacerotidae, Dana Report, 64 1–92. • Gaudant, J., Delrieu, B., & Dermitzakis, M.D. (1994): Decouverte d’une ichthyofaune marine dans les diatomites du Pliocene superieur (Plaisancien) des environs d’Heraklion (Crete centrale). –C. R. Acad. Sci. Paris, 319 (II): 589-596, 7 fig.-Paris Prassas 2 46.1% 26.1% 13.8% - 26.1%

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