ABAH BIOFLUX2010/02/27 · Rezumat. În vestul Bazinului Dacic romanianul începe cu o faună de unionizi sculptaţi şi viviparide robuste, care apar în numeroase aflorimente din

ABAH Bioflux, 2010, Volume 2, Issue 1. http://abah.bioflux.com.ro

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ABAH BIOFLUX Animal Biology & Animal Husbandry International Journal of the Bioflux Society Contributions to the knowledge of the Romanian from the western Dacian Basin: The molluscs’ fauna from Răcarii de Jos (Dolj County) Tudor C. R. Pătruţoiu, and Ion Pătruţoiu

SC Explo 06 SRL, Craiova, Romania, European Union. Corresponding author:

I. Pătruţoiu, [email protected]

Abstract. In the western Dacian Basin, the Romanian age starts with a fauna comprised of carved unionidae and robust viviparidae, which appear in numerous crops in Mehedinţi, Dolj and Gorj Counties. The lamellibranchiate species from Răcarii de Jos are replenishing the Romanian palaeontology inventory and are offering new data about the evolution of the retreating Pliocene lake to the east due to the Vlach orogenesis that carried forward with the ascend of the Carpathian Mountains. Key words: fauna, lamellibranchiate, Romanian, Dacian Basin. Rezumat. În vestul Bazinului Dacic romanianul începe cu o faună de unionizi sculptaţi şi viviparide robuste, care apar în numeroase aflorimente din Mehedinţi, Dolj şi Gorj. Formele de lamelibranchiate de la Răcarii de Jos completează inventarul paleontologic romanian, oferă noi date despre evoluţia lacului pliocen în retragere spre est datorită orogenezei valahe care a continuat ridicarea Carpaţilor. Cuvinte cheie: faună, lamelibranchiate, romanian, Bazin Dacic.

Introduction. The Dacian Basin is expanding in the south-western region of Romania, being partially superposed by the Romanian Plane. It had a specific evolution from Pontian to Quaternary (Teissezre 1907; Macovei 1954; Popescu & Diaconu 2002). The Romanian formations, mostly unconsolidated or weakly consolidated detritus are fine or coarse and are comprised by lamellibranchiate, gastropods and micromammals from palaeontological point of view.

The research over the Levantine, later Romanian formations started as far back as 1894 when Bielz & Czekelius (cited by Porumbaru 1881) determined some forms in the Bucovăţ fossiliferous point.

In 1881, R. Porumbaru publishes the study named “Etude geologique des environ de Craiova, parcours Bucovăţ-Cretzeşti“.

Further studies about the Levantine fauna appeared subsequently being signed by Sabba-Ştefănescu (1896), Ionescu-Argentoaia (1918), Wenz (1942), Pană et al (1981), Enache et al (2001), Andreescu (1982).

Răcarii de Jos Collection Site. It was identified by us in the vicinity of an exploitation of sand and gravel, in a seasonal valley, found at the edge of the village. One can arrive at this place from the roadway DN6 Brădeşti - Filiaşi, then right on the street that crosses the Răcarii de Jos village. After 1300 m from the roadway there is an abruption on a slope at about 9 m in height that has a fossil level in a fine sand housing. The fossils are comprised of carved lamellibranchiate forms, which are relatively well preserved.

In the western Dacian Basin, the Romanian age starts with deposits formed mostly from unconsolidated or weakly consolidated detritus that are rich in molluscs. In these fossil molluscs the lamellibranchiate are predominant (see also Pavnotescu 1995), following the gastropods.


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Figure 1. The location of Răcarii de Jos fossiliferous place.

Figure 2. The lithological composition of Răcarii de Jos Exposure.

Results and Discussion Bivalvia Fauna – General Description


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Family UNIONIDAE Subfamily PSILUNIONINAE

Genus Rytia, Sabba-Ştefănescu 1896 Rytia slavonica ( M. Höernes) 1855

Pl. 1, figs 7-8; Pl. 2, fig. 3

1855 Unio slavonicus, M. Höernes (cited by Roşculescu & Huică 1972), p. 291, pl. 37, fig. 7.

1883 Unio slavonicus, Peneke, p. 89, pl. 19, figs 11-13. 1981 Rytia slavonica, Pană, Enache, Andreescu, p. 34, pl. 17, fig. 1-5. 1998 Rytia slavonica, Pătruţoiu, Stamate, Meilescu, p. 76, pl. I, figs 4-11; pl.

II, figs 1-4. 2000 Rytia slavonica, Pătruţoiu, p. 122, pl. 8, figs 7-11; pl. 9, figs 1-4.

The shell is robust, triangular and rounded. The umbone is slightly curved. On the external face it presents growth striae that are well outlined, which in the posterior area delimit two careens that start from the umbonal area. In the medial area, it presents growth nodules that are radial oriented towards the two careens.

The right valve has a triangular crenulated cardinal tooth, which is placed in the internal subumbonal area, and a lamellar lateral tooth, that ends in the medial posterior area of the shell.

The left valve has two unequal cardinal teeth, the posterior one being the most potent, and two lateral teeth that are quasi equal.

The impression of the anterior muscle is triangular and deep and it placed in the prolongation of the cardinal teeth. The impression of the posterior muscle is more faded, bigger and quasi round.

It differs from R. brandzae (Sabba-Ştefănescu) by means of the more rounded form.

Răcarii de Jos-Dolj. Romanian.

Subfamily UNIONINAE

Genus Pristinus Starobogatov, 1970 Pristinunio davilai (Porumbaru, 1881)

Pl. 1, figs 1-4; Pl. 2, figs 5-8

1881 Unio davilai, Porumbaru, p. 15, pl. 1, figs 1-3. 1942 Unio pristinus davilai, Wenz, p. 107, pl. 52, figs 567a-d. 1981 Pristinunio davilai, Pană, Enache, Andreescu, p. 55, pl. 3, figs 1-3; pl. 4,

figs 1-4; pl. 5, figs 1-2. 1998 Pristinunio davilai, Pătruţoiu, Stamate, Meilescu, p. 77, pl. IV, figs 1-4;

pl. V. figs 1-8. 2000 Pristinunio davilai, Pătruţoiu. p. 91, pl. 11, figs 1-4; pl. 12, figs 1-8.

The shell is large, elongated, with elliptical valves, not equilateral, with two asymmetrical parts. The anterior part is short, while the posterior one is elongated, sometimes slightly curved. The maximum length of the shell is 70-72 mm. On the external surface, the valves present thin growth striae.

The right valve has a strong cardinal tooth, placed in front of the umbone and an elongated lateral tooth.

The left valve has two cardinal teeth and two lateral teeth, the anterior one being the tallest.

The impression of the anterior muscle is deep, placed in front of the two cardinal teeth. The impression of the posterior muscle is big and elongated.

It is bigger and more elongated than P. pristinus (Bielz). Răcarii de Jos - Dolj. Romanian.


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Pristinunio pristinus (Bielz, 1864) Pl. 1, figs 5-6; Pl. 2, figs 1-2

1864 Unio pristinus, Bielz, pl. 15, fig. 243. 1918 Unio pristinus, Ionescu-Argentoaia, p. 408, pl. XI, figs 1-4. 1942 Unio pristinus, Wenz, p. 107, pl. 52, figs 565-566. 1980 Pristinunio pristinus pristinus, Nicolaescu et al, pl. III, fig. IV. 1981 Pristinunio pristinus, Pană, Enache, Andreescu, p. 55, pl. 1, figs 1-4; pl.

2, figs 1-5. 1987 Pristinunio pristinus, Lubenescu et al, pl. III, fig. 13. 1989 Pristinunio pristinus, Papaianopol, p. 54, pl. XXXV, figs 1-4. 1998 Pristinunio pristinus, Pătruţoiu, Stamate, Meilescu, p. 77, pl. II, figs 5-8;

pl. IV, figs 5-6. 2000 Pristinunio davilai, Pătruţoiu, p. 91, pl. 9, figs 5-8; pl. 11, figs 5-6.

The shell is of small or medium size, up to 60-65 mm, oval elongated, with the umbone weakly outlined, placed in the anterior part of the shell, part that represents one quarter of the entire length. The external surface has growth striae that are weakly outlined.

The dentition is unionidae type. The right valve has a cardinal tooth and a lateral one, both of them very well outlined.

The left valve has two cardinal and two lateral teeth. The impressions of the adductor muscles are very well outlined, the one of the

anterior muscle being deeper and placed in front of the cardinal teeth. The impression of the posterior muscle is more elongated and bigger.

The ligament area is well outlined, developed on about half length of the shell. It is differentiated from P. davilai by its less elongated form towards the posterior

side. Răcarii de Jos-Dolj. Romanian.

Conclusions Palaeontological Considerations. The geotectonic evolution of the western territory of the Dacian Basin knows an important step at the end of the Pontian, when the bond with the Pannonic Basin breaks definitively. The breaking of this bond marks the accentuated process of irreversible water sweetening which were until then salmaster. After that, there was a period when the limits of the Pliocene lake were in slow motion towards the east, being alternated oscillatory sequences at Dacian and Inferior Romanian level where there were created conditions for carbon-generating pools in extended territories. The coal beds found in all over Oltenia pleads for this situation.

At the end of the Dacian, there was a short period of emergence, when there was formed the relief over which the Romanian deposits were positioned. The Romanian waters transgressed the emergence area, thus starting a sedimentation cycle. The Romanian starts in the western area of the Dacian Basin with the carved unionidae fauna, horizon which is found in the whole area. In the Romanian, the lake knows stagnancy sequences with shallow waters, conditions that are found in the faunistic evolution too.

The general tendency is the retreat of the waters to the east, phenomenon generated by the tectonic movements of the Vlach orogenesis that produced the elevation of the Carpathians. The robust forms, well developed, in the stagnancy sequences indicate a period of evolutional calm, with proper conditions for sweet, shallow but agitated waters.

The lamellibranchiate fauna with Unio, Psilunio, Pristinunio, Rytia, Cuneopsidea, Sulcopotomida and gastropods from viviparidae family, indicates such conditions. The fossiliferous places from Bucovăţ, Sărbătoarea, Podari, Brădeşti, Buiceşti, Scoruşu, Gârbovu etc are well known.

The Răcarii de Jos fossiliferous place is inscribed as a new element which enriches this species list (see also Plates 1-2, below).


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Plate no. 1

Pictures 1-4. Pristinunio davilai (Porumbaru), X 1, Răcarii de Jos, Romanian

Pictures 5-6. Pristinunio pristinus (Bielz), X 1, Răcarii de Jos, Romanian Pictures 7-8. Rytia slavonica (M. Hörnes), X 1, Răcarii de Jos, Romanian


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Plate no. 2

Pictures 1-2. Pristinunio pristinusi (Bielz), X 1, Răcarii de Jos, Romanian Picture 3. Rytia slavonica (M. Hörnes), X 1, Răcarii de Jos, Romanian Pictures 4-8. Pristinunio davilai (Porumbaru), X 1, Răcarii de Jos,

Romanian


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Received: 03 April 2010. Accepted: 05 July 2010. Published online: 06 July 2010. Authors: Tudor Ciprian Radu Pătruţoiu, SC Explo 06 SRL, Dr Victor Papillian Street, No 52, Bl G6, Sc 1, Ap 3, Craiova, Romania, European Union, e-mail: [email protected] Ion Pătruţoiu, SC Explo 06 SRL, Dr Victor Papillian Street, No 52, Bl G6, Sc 1, Ap 3, Craiova, Romania, European Union, e-mail: [email protected] How to cite this article: Pătruţoiu T. C. R., Pătruţoiu I., 2010 Contributions to the knowledge of the Romanian from the western Dacian Basin: The molluscs’ fauna from Răcarii de Jos (Dolj County). ABAH Bioflux 2(1):27-34.

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ABAH BIOFLUX2010/02/27 · Rezumat. În vestul Bazinului Dacic romanianul începe cu o faună de unionizi sculptaţi şi viviparide robuste, care apar în numeroase aflorimente din