The smallest late Miocene phocine from the Southern Caucasus and the Eastern Paratethys seal community crisis

ABSTRACT The Caucasus is one of the most important areas for the study of Paratethyan Neogene phocids, with a number of ‘paleorookery’ sites that are still poorly studied. In this study, the remains of a fossil phocine from the Late Miocene locality of Eldari I (late Vallesian/late Sarmatian s.l.) in the Southern Caucasus are described and compared with other Paratethyan phocines. The new materials obtained from the site consists of the right complete forelimb bones along with the carpal and metacarpal bones in natural anatomical articulation and a right innominate bone fragment. Additionally, published remains of ‘Phoca’ procaspica from Eldari I are analysed. Based on morphological and morphometric studies, the Eldari I phocine is assigned to the genus Praepusa. The skeletal material demonstrates a distinct combination of diagnostic traits that can be attributed to the smallest representative of the subfamily, Praepusa procaspica. During the early Late Miocene (10 Ma.), major palaeoecological and palaeogeographic changes took place in the Eastern Paratethyan basin, which significantly decreased the diversity of phocids and had a negative impact on the remnant taxa; this was expressed in the Eldari I and Küçükçekmece seals by the decrease in body size and a change in the feeding apparatus. urn:lsid:zoobank.org:pub:497DEEE9-8557-4136-8AD7-B8749A0285A2


Introduction
According to the existing data (Grigorescu 1976;Koretsky 2001;Koretsky and Barnes 2006;Koretsky and Ray 2008;Dewaele et al. 2017), fossil seals were widespread on the Western Eurasian Neogene (Middle-Late Miocene and Early Pliocene) basin shores, nevertheless, phocid remains are quite rare.Consequently, the systematic and phylogenetic aspects of phocids and in general semi-aquatic carnivores are insufficiently known.One of the important areas for the Late Miocene phocids research is the Western part of the Eastern Paratethys basin (the northern littoral region of the Black Sea; Figure 1a).In this region, the diversity of the Middle-Late Miocene Phocinae has been confirmed, as at least seven taxa (Histriophoca alekseevi, Monachopsis pontica, Praepusa pannonica, Praepusa vindobonensis, Cryptophoca maeotica, Sarmatonectes sintsovi, Planopusa semenovi) from various sites are known (Grigorescu 1976;Koretsky 2001;Koretsky and Barnes 2006;Koretsky and Rahmat 2021).In contrast to the Western part of the Eastern Paratethys basin, the remains of fossil seals found in the Eastern area of the basin (the Caucasus and the Caspian sea basin) are deficiently studied.The only exception is the material from the Mangyshlak Peninsula (Kazakhstan), where the description and taxonomic affiliation (Praepusa vindobonensis) of fossils are established (Koretsky 2001).In the Caucasus, the presence of phocids fossils have been reported periodically; however, the fossil seals from this region are poorly known.In the Middle and Late Miocene deposits of the northwestern Caucasus, fossil seal remains have been found in Stavropol, Maikop, Armavir, Kutsay, and Kosyakin localities (Ivanov 1916;Vereshchagin 1959;Kirpichnikov 1961;Meladze 1985).In most of these findings, the exact stratigraphic and geographic position of the locality and anatomical features of the material remain unknown.In the Southern Caucasus, fossil phocids are found in Georgia and Azerbaijan.Bogacheva (1927) describes coprolites and postcranial remains of seals collected among emissions of the Lok-Batan (the Apsheron Peninsula, Azerbaijan) mud volcano.This material includes the distal ends of two left humeri bones and two fragments of the right femur.Based on the dimensions of the material, Bogachev attributes one fragment of the left humerus and the right femur to 'Phoca' pontica (Monachopsis pontica), while emphasising the resemblance of the second fragment of the humerus with 'Phoca' vindobonensis (Praepusa vindobonensis).It is difficult to determine the geological age of the fossil material from the Lok-Batan mud volcano emissions, but we agree with Bogachev's attribution of the material to the Miocene age according to the fossil cetacean material (Cetotherium sp. and Cetotherium mayeri) found at the site (Bogacheva 1927(Bogacheva , 1938)).Bogachev also reported middle Sarmatian (s.l.) fossil seal remains in the Kiliazinsk spit limestone deposits on the northern coast of the Apsheron Peninsula (Bogacheva 1938).Unfortunately, a description or illustration of this find has not been published; the author only noted the site location and attributed the remains to Phoca sp.An additional seal fossil (a distal right fibula) was found in the upper part of the Maykopian clay deposits (Late Oligocene-Early Miocene) of the Perekishkul site (Aslanova 1965).In describing this fossil, Aslanova (1965) notes the very small size (without giving morphometric data) and primitive character of the fibula, and its close morphological affinities with recent Pusa caspica, but does not assign it to any known taxon of phocids.
In the South Caucasus, one of the most important fossil phocid finds is from the late Sarmatian (s.l.) site Eldari I (Figure 1b).The remains of a seal from Eldari I were first discovered in 1938 during a joint excavation conducted by the Geological Department of the Janashia State Museum of Georgia (M.Popkhadze and N. Burchak-Abramovich) and the Schmalhausen Institute of Zoology of the National Academy of Sciences of Ukraine (I.Pidoplichko).Additional materials were obtained by subsequent field campaigns (Burchak-Abramovich 1954a;Gadzhiev 1961;Meladze 1985;Tsiskarishvili 1987).The taxonomic affiliation of the Eldari I seal has long been unknown.Gadzhiev (1961) initially attributed the phocid material to a new species, 'Phoca' procaspica, without giving any criteria for determination or description; the description of the material was published later (Gadzhiev 1997).However, the species determination rationale, type specimen, inventory numbers, or institution where the collection is housed have not been indicated.Consequently, the affiliation of the genus and the validity of the species remain undefined.Recently, new fossil phocid material from Eldari I have been obtained and consist of the well-preserved complete right forelimb bones in anatomical articulation, a scapula of the same individual, an incomplete innominate bone, and carpalmetacarpal bones in natural anatomical position (Figure 2-4).Unlike the other fossil phocid records in the region, the Eldari seal materials are found along with the remains of fossil terrestrial vertebrates (Eldari I), which allows us to determine its biochronological age more precisely.The circumstance with the remains of 'Phoca ' procaspica (Gadzhev 1997) and the presence of new fossils make it necessary to reconsider the taxonomic affiliation of the Eldari I seal material and to determine its systematic position.

Material and methods
The present study is based on the fossil Phocidae collection from the Eldari I site, which comprises: the right forelimb bones (humerus, ulna, radius, scapholunar, trapezium, I-V metacarpals, I-V first phalanx, II-V second phalanx, IV-V third phalanx) and scapula (El-I 1 IPB); a right innominate bone fragment (El-I 2 IPB); right carpal (pisiform, capitatum, scapholunar, trapezoid, trapezium) and I-V metacarpal bones (El-I 52 IPB).The specimens El-I 1 IPB and El-I 52 IPB are found in natural anatomical articulation.The collection is housed at the L. Davitashvili Institute of Palaeobiology (Georgian National Museum).Additionally, the morphological analysis provided here includes the specimens published by Gadzhiev (1997), which consists of the rostral part of the cranium, a hemimandible (A) fragment with teeth row p2-m1, a hemimandible (B) fragment with teeth row p4-m1, the distal part of the tibia, and the head of the femur.
This study uses comparative morphological analysis methods and anatomical terminology according to Koretsky (2001) and Dewaele et al. (2017).Upper teeth are abbreviated with capital letters and lower teeth with lower case letters.All measurements are in millimetres and were taken using a digital calliper to the nearest 0.1 mm following the methodology of Koretsky (2001).

Geological settings and age of the site
The Eldari I site is located in eastern Georgia on the right bank of the Iori River in the western part of the Eldari ridge (=Ellyar-oyugi), which is the southern range of the Eldari lowland (Figure 1b).The Eldari ridge was formed by marine and continental sedimentary rocks of the Eldari formation (Andrianov and Larin 1935).The Eldari formation is divided into three sections/units (Dombrovskii 1914;Andrianov and Larin 1935;Burchak-Abramovich 1954a;Gabunia 1959;Tsiskarishvili 1987;Vangengeim et al. 1989;Chkhikvadze et al. 2000).The lowermost section (unit I) is exposed at the southern slope of the Eldari ridge and represents dark-grey clay deposits with the middle Sarmatian (Bessarabian) molluscan fauna (Cryptomactra pesanseris), the benthic foraminifera (Gabunia 1959;Vangengeim et al. 1989), and cetacean remains (Dombrovskii 1914;Gadzhiev 1997).The second section (unit II) is represented by the succession of sandy clays, sands, and sandstone deposits, with the late Sarmatian (Khersonian) molluscan fauna remains (Mactra caspia and Mactra bulgarica).Unit II represents a rich vertebrate fossilbearing (Eldari I site) horizon, where the majority of vertebrate faunal remains belong to terrestrial mammals, with the exception of one marine mammal, 'Phoca' procaspica.In previous publications (Tsiskarishvili 1987;Chkhikvadze et al. 2000;Bukhsianidze and Koiava 2018), the phocid remains were erroneously assigned to the lowermost middle Sarmatian (Bessarabian) fossil-bearing deposits (unit I) with cetacean records of the Eldari formation.In reality, all the known Eldari seal fossils are found only in the late Sarmatian (Khersonian) deposits along with terrestrial vertebrates (Burchak-Abramovich 1954a, 1954b;Gadzhiev 1961Gadzhiev , 1997)).This context was confirmed during the preparation of the phocid fossils-bearing sandstone blocks (El-I 1 IPB, El-I 52 IPB; Figure 4), as the blocks contained the fossil bones of land mammals and shells of the late Sarmatian (s.l.) Mactra caspia and Mactra bulgarica (identified by L. Muskhelishvili).The uppermost section (unit III) was formed by continental variegated clays with intercalations of sandstone deposits (Andrianov and Larin 1935).In this section, abundant macropaleobotanical materials and two terrestrial vertebrate fossil-bearing horizons (Eldari II and Eldari III sites) were found (Gabunia 1959;Tsiskarishvili 1987;Vangengeim et al. 1989;Chkhikvadze et al. 2000).The age of this uppermost section remains uncertain; some researchers consider it to be late Sarmatian (s.l.) freshwater deposits (Buleishvili 1960;Chubinishvili 1982;Meladze 1985), while others propose that it is early Meotian (Tsiskarishvili 1987(Tsiskarishvili ,1992;;Vangengeim et al. 1989, ;Chkhikvadze et al. 2000).
Type locality and Geological age: all studied materials in the present work are found at the locality Eldari I (Georgia, Southern Caucasus), in the late Sarmatian (late Vallesian, MN 10) sandstone deposits of the Eldari formation (section II).
Remark: Since the author of the species (Gadzhiev 1961(Gadzhiev , 1997) has not specified the type specimen, the material numbers and an institution where the collection is deposited, attempts to find the collection were unsuccessful.Hence it is expedient to establish the neotype specimen.The etymology of Pr. procaspica is proposed based on similar morphological characters of the Eldari fossils with the recent Caspian seal, Gadzhiev (1959Gadzhiev ( , 1961Gadzhiev ( , 1997) ) considers the Eldari seal as a direct ancestor of Pusa caspica.
Emended diagnosis: A small-sized Phocinae, with a chin prominence located under the posterior edge of p4; the labial surface of mandibular ramus is convex and the lingual surface is concave; the length of the alveolus m1 exceeds the length of the alveolus p4; the diastema between p2 and p3 is the largest and the diastema between p4 and m1 is the smallest; the diastema between p4 and m1 is shorter than diastema between p3 and p4; the lesser tubercle height does not reach the proximal edge of head; the greater tubercle is located proximally than the lesser tubercle, at the level of the head; the head is mediolaterally compressed, and the ratio of the head's width to its height is 0.976.

Description
El-I 1 IPB -The nearly complete right forelimb and scapula of a relatively small-sized seal.The bones are enclosed in a consolidated sandstone block; due to the fragility of the fossil material, it was not separated completely from the sediment.The limb and scapula lie on the lateral side and only the medial side is visible (Figure 2).All bones except the scapula are in natural anatomical articulation.The scapula is displaced from its anatomical position and turned forward, with its supraglenoid tubercle attached to the proximal surface of the humerus head and the proximo-anterior edge of the medial surface disposed under the carpal bones.The carpals are partly visible, but the scapholunar and trapezium bones can be clearly distinguished.The long bone epiphyses are fused, although sutures of fusion are observable on the distal segments of the limb, indicating a sub-adult individual.
The scapular neck is narrow and somewhat elongated.The neck is about one-third of the bone length.The deep and wide subscapular fossa is stretched from the neck to the proximal edge.The caudal angle has a sharp, somewhat curved-beak shape.The glenoid fossa is deep and concave with a wider posterior part.It has an elongated triangular shape with a straight medial edge, a slightly curved lateral edge, and short caudal edges.The glenoid tubercle is well-developed.
The humerus is slender, with less mediolateral width (Table 1) in the diaphysis (the bone does not show any deformation or compression).The lesser tubercle, although broken at the tip, is wellexpressed and elongated along the bone axis.Its height does not reach the proximal edge of the head and is distal to the greater tubercle.The intertubercular groove is narrow.The humerus head is mediolaterally compressed, and its ratio (width to height) is 0.976.The slender deltoid crest in the medial view is smooth and it is not bent medially.The deltoid crest gets its maximal width at the level of the lesser tubercle base.In length, the crest is about two-thirds of the bone length and has a sharp edge on both the distal and proximal portions.Distally, it smoothly descends at the deep coronoid fossa.The bone is broken from the proximal base of the entepicondylar foramen bridge to the medial border of the olecranon fossa, so the medial epicondyle and condyle are missing.The lateral epicondyle is well-developed and has a sharp crest that reaches the middle of the diaphysis and smoothly ends at the level of the distal part of the deltoid crest.The olecranon fossa is shallow and poorly expressed.
The distal half of the ulna is rounded and robust; in contrast, the proximal half is thin and flattened.The caudal portion of the olecranon is broken, but the anterior part is well-developed and thickened.The olecranon tuberosity is prominent.The greater sigmoid cavity is wide and elongated.The anconeal process is well developed and is located slightly forward over the coronoid process.The coronoid process is considerably expressed and projects medially.The radial notch is deep.Under the coronoid process, the proximodistally elongated wide groove is present with a strong crest on its caudal edge.The groove and crest smoothly descend onto the rounded surface of the diaphysis.The distal epiphysis is robust with a strong and short styloid process.
The radius is slender and small; the distal portion of the bone is wide and robust with a smooth medial surface.The proximal portion is rounded and much smaller.The medio-caudal edge of the bone is slightly curved, in contrast to the medio-cranial edge, which has an open-angle protuberance in the middle of the diaphysis.The radius head is small with a well-expressed articular circumference.The ulnar articular facet is not widely stretched onto the medial surface and it is only slightly visible on the medio-caudal edge of the radial head.The bicipital tuberosity is not prominent.The distal epiphysis is much smaller than the distal shaft of the bone.The tendon groove for the musculus abductor pollicis longus is not deep and weakly exposed.The surface for articulation with the carpal bones is wide and takes more than two-thirds of the epiphysis Table 1.Measurements (in mm) of the forelimb segments (El-I 1 IPB) of Praepusa procaspica from the Eldari I site; Scapula: 1 -greatest length; 2 -width of collum; 3anteroposterior diameter of cavitas glenoidale; 4 -transversal diameter of cavitas glenoidale.Humerus: 1 -greatest length; 2 -length of deltoid crest; 3 -height of head; 4 -height of trochlea; 5 -width of head; 6 -transverse width of diaphysis; 7 -thickness of proximal epiphysis; 8 -thickness of medial condyle; 9 -diameter of diaphysis with deltoid crest.Ulna: 1 -greatest length; 2 -width of incisura trochlearis in upper part; 3 -maximal width of middle part of diaphysis; 4 -maximal width of middle part of distal epiphysis; 5 -width of bone at the level of lower part of incisura trochlearis; 6 -width of olecranon; 7 -transverse diameter of proximal epiphysis at the level of processus anconeus.Radius: 1 -greatest length; 2 -width of diaphysis; 3 -width of distal epiphysis; 4 -width of articulation surface of distal epiphysis; 5 -lesser diameter of caput; 6 -least width of proximal epiphysis.Metacarpals and phalanges: 1 -greatest length; 2 -width of proximal end; 3 -width of distal end; 4 -width of diaphysis.Asterisks indicate approximate dimensions taken from the bone imprint.El-I  length.The styloid process is not large and it is slightly higher than the distal edge of the ulnar notch.The ulnar notch is prominent.The distal epiphyses of the ulna and radius are fused, but the line of fusion is still well-defined.
The carpal bones are represented by the scapholunar and trapezium bones.The scapholunar is robust and elongated transversely, with proximolaterally swollen protuberance.The articular surface for the radius is a concavo-convex shaped facet.The triangular trapezium bone is positioned distally and possesses a wider distal articular facet for Mc I and a smaller proximal bilateral facet for the scapholunar and Mc II bones.The metacarpal bones are small and slender.The metacarpal I is the largest and is somewhat flattened dorsoventrally.The proximal portion of the metacarpal I is slightly curved medially, the proximal epiphysis is not completely fused, and the distal epiphysis is comparatively smaller but completely fused.In contrast to the first metacarpal, the diaphyses of metacarpals II-V have a straight and rounded shape with mediolaterally compressed proximal ends.The distal ends of all metacarpals have a trochlear shape.On the distal articular surface, ventrolateral and ventromedial condylar regions are wide, the sagittal crests are prominent and sharp-edged, and the parasagittal grooves are deep and open.Only the third metacarpal has preserved tear-shaped proximal sesamoid bones.The first, second, and third ungual phalanges are absent.The first phalanx of the first digit is large, flat, and elongated.Compared to other phalanges, it is twice as long and wider.The proximal II-V and middle II-V phalanges are slender, dorsoventrally flattened, and straight.The distal and proximal articular ends have a broad trochlear form.The fourth ungual phalanx has a robust base with a weakly developed ungual crest and the fifth ungual phalanx is slender and lacks an ungual crest.
El-I 2 IPB -The right incomplete innominate bone preserves the basal articular portion with broken branches of the ischium and pubis, but it lacks the winged portion of the ilium (Figure 3).The bone is broken medially at the middle dorsoventral line of the acetabulum so the lateral, anterior parts of the acetabular rim remain.The iliopectineal eminence is massive but not strongly projecting.The acetabulum is circular and deep, and the acetabular notch is very narrow.The obturator groove is wide and strongly deepened on the lateral surface.The pubis branch is slender and mediolaterally flattened; on its internal edge, the external obturator muscle fossa is prominently marked.The anterior part of the ischium is massive, has a triangular form in the transversal section, and is posteriorly flattened mediolaterally.The sciatic notch is well developed.
El-I 52 IPB -The specimen is represented by the right carpal (scapholunar, trapezoid, trapezium, hamate, and pisiform) and metacarpal I-V bones in natural anatomical articulation.Similar to the above-described fossils (El-I 1 IPB), the autopodium bones are also ventrally enclosed in the consolidated sandstone block and only the dorsal view is observable (Figure 4).The metacarpal epiphyses are completely fused and an epiphyseal suture is not expressed, thus the individual is an adult.The scapholunar is mediolaterally elongated, massive, and robust.The lateral protuberance in the dorsal aspect is oriented distally and is slender in contrast to the medial portion of the bone.The articular facet for the radius has a concavo-convex surface and is wide.The rough dorsal surface is prominent.The articular facet for the trapezoid is narrow and elongated transversally.The smaller articular facet for the hamate is situated on the medial surface of the bone.The trapezoid is rectangular, mediolaterally elongated, and has broad proximal and distal articular facets for the scapholunar and trapezium bones.On the trapezium bone, the articular facet for the first metacarpal has a transversally elongated concave surface, medially shorter articular facet for the second metacarpal bone is placed.The hamate is rhomb-shaped and oriented medially from the scapholunar bone.The pisiform is elongated laterodistally.The dorsal parts of the capitatum and triquetrum bones are eroded and poorly observable.The metacarpals are robust and compactly arranged, in contrast to the subadult individual El-I 1 IPB, in which metacarpals are slender and expanded (Figures 2 and 4).The first metacarpal is large and dorsoventrally flattened; the curvature of the medial edge is not pronounced.The proximal epiphysis has a triangular shape with a broadly projected lateroproximal portion.The proximal shaft of the second metacarpal is medioproximally extended.The proximal structure of the first and second metacarpals forms an arcuate articular recess for the trapezium.The first metacarpal is the longest and metacarpals II-V are progressively shorter (Table 2).The diaphyseal shafts of metacarpals II-V are straight and rounded with broad, trochleated distal epiphyses.Articular facets for the first phalanx are wide with prominent sagittal crests.Only the proximal part of the first phalanx on the second digit is present, which possesses a wide articular surface and deep groove for the metacarpal sagittal crest.In addition to the preserved bones, imprints of the distal portions of the radius and ulna are preserved.The ulna bone shaft imprint has a slightly curved medial surface and the styloid process is not marked.The imprint of the distal portion of the radius is markedly wide (the maximal width is 27.77 mm) and its ulnar notch impression is prominently broad.

Comparison and discussion
In addition to the new material described above, here we revise the published remains of the Eldari I seal (Gadzhiev 1997).Based on the fragmentary material, Gadzhiev (1961) named the new species, Phoca procaspica, without giving diagnostic morphological characters of the taxon.Later, the author briefly described the fossils, noting their very small size: The cranium fragment is represented by the visceral part, which is broken off at the posterior edge of the orbits.The nasal, maxilla and a portion of the frontal bones are well preserved, while the premaxilla bones are missing.The anterior nasal bones are relatively broad and gradually narrow posteriorly, the posterior ends of the nasal bones are wedged into the frontal bone and the frontonasal suture is not pronounced.The nasal-maxillary sutures are prominent, and the anterior edges of the nasal bones are broken.The maxillary bones sharply taper anteriorly, but they are somewhat widened closer to the nasal bones.The left and right alveolus of P3-M1 on the maxillary bones are preserved, and the alveolus of M1 remarkably deviates labially from the premolar alveoli row.There is a depression along the line corresponding to the seam between the palatine processes, but the seam, due to its fusion, is not noticeable.From the frontal bone, only the part of the orbit and pars nasalis is preserved.The pars nasalis has a strongly elongated triangular shape.The orbits are oval, anteroposteriorly elongated, and reach their greatest height slightly anterior to the middle axis.Two fragments of mandibles are represented: one of them is broken distally from the m1, preserving the p2-m1 with the canine and p1 broken at the root, and the second fragment is the posterior half of the mandibular ramus with p4 and m1.The mandibles are comparatively short with a convex labial surface and a concave lingual surface, the chin prominence, which is located under the p4 posterior edge, is especially inward and the mandible reaches its greatest height at this point.Only two mental foramina are clearly visible.The alveolus of the c is located obliquely with respect to the sagittal plane of the mandible.The diastema between the alveolus of c and p1 is larger than between other teeth, the alveolus of p1 is rounded.The diastema between p1 and p2 is insignificant and only slightly exceeds the diastema between p4 and m1.The diastema between p2 and p3 is the largest among premolars.The premolars are heavily worn, however, the anterior and main cusps are visible on the p2, the p4 is less worn, and the main, anterior, and posterior cusps are clearly visible.The diastema between p4 and m1 is the smallest.The femoral head is rounded with a triangular fovea.The tibia is represented by the distal epiphysis and the fusion line between the diaphysis and the epiphysis is not visible.The articular surface for the astragalus bone is oval-shaped and elongated dorsoplantarly, outward from the articular surface rises the processus malleolaris (Gadzhiev 1997, pp. 47-48).
Regardless of the changes in the generic reassessment of the Caspian seal (from Phoca into Pusa), the generic affiliation of 'Phoca' procaspica has never been the subject of discussion.Undoubtedly, the Eldari I fossil seal record belongs to the representative of the subfamily Phocinae based on the main anatomical traits of the subfamily: such as the shape of a maxilla and narrow elongated rostral part, slenderer structure of the limb bones, presence of an entepicondylar foramen, well developed epicondylar crest, the shape and form of the deltoid crest (Chapskii 1955(Chapskii , 1974;;Koretsky 2001;Koretsky and Rahmat 2013;Koretsky et al. 2016Koretsky et al. , 2020;;Churchill and Uhen 2019;Azizah et al. 2020).
Here it is considered necessary to compare our material and the published data with the late Middle and Late Miocene (Sarmatian s. l.) representatives of the subfamily Phocinae from the Central and Eastern Paratethys.Most of the known extinct genera from this area exhibit distinct morphometrical and morphological features.Unfortunately, there are no suitable materials to compare Planopusa semenovi with Pr. procaspica, as only fragmentary (fragment of the skull rostral part and isolated teeth) records are known from the taxon (Koretsky and Rahmat 2021).Histriophoca alekseevi (Koretsky 2001) is also represented by few remains, but it is still possible to distinguish these two forms.The alveolar row on the skull of H. alekseevi is in a straight line, while in Pr. procaspica, the M1 alveolus deviated labially from the premolar alveolar row.The p4 of H. alekseevi has only one cusp, while Pr.procaspica has three cones on the p4 (Gadzhiev 1997).The shallow chin prominence is located under m1 on the mandible of H. alekseevi (Koretsky 2001), and on the mandible of Pr. procaspica, it is under the posterior part of the p4 (Gadzhiev 1997).Another poorly known phocid from the late Middle Miocene deposits of the Eastern Paratethys is Sarmatonectes sintsovi, which differs from Pr. procaspica by having considerably greater dimensions and craniocaudally compressed head of the humerus (Koretsky 2001).However, we abstain from comparing the remains of Pr. procaspica with the humerus of S. sintsovi until more data are available from this taxon.The fossil record of Pr. procaspica differs from the material of Cryptophoca maeotica in several morphological traits: the chin prominence placed between p3 and p4; the lingual surface of the mandible is flat; the alveolar length of m1 is smaller than that of p4; the humerus head is rounded; the deltoid crest is long and wide, and it takes up to 1/4 of the humerus length; the lesser tubercle located higher than the head, at the same level as the proximal border of the deltoid crest; the intertubercular groove is only slightly discernible (Koretsky and Ray 1994;Koretsky 2001;Peigné 2016).Besides these features, there are marked differences in size and robusticity between these phocids (Figure 5).One of the well-known smallsized Phocinae from the Eastern Paratethys is Monachopsis pontica.Despite the similarity in dimensions, its morphological features are significantly different from Eldari I phocid remains.The tooth-row of M. pontica is on a straight line (Koretsky 2001), while on the maxilla of Pr. procaspica, the M1 alveolus has an appreciable swerve to the labial side (Gadzhiev 1997).On the humerus of M. pontica, the lesser tubercle is located higher than the humerus head, is bent backwards and laterally, and is on the same level as the proximal part of the deltoid crest.The head is dorsoventrally compressed, and the intertubercular groove is wide and flat (Koretsky 2001).In contrast to the El-I 1 IPB on which the lesser tubercle is not bent, its height does not exceed the proximal edge of the head and is below the greater tubercle.The head is mediolaterally compressed, and the intertubercular groove is comparatively narrow.
In Western Eurasia, another rich Late Neogene phocine recordbearing region is the eastern shore of the North Atlantic.Mostly based on Van Beneden's collection, five genera (Platyphoca, Gryphoca, Phocanella, Batavipusa, and Nanophoca) of the subfamily have been described from this area (Van Beneden 1877; Koretsky and Peters 2008;Koretsky and Ray 2008;Koretsky et al. 2014;Dewaele et al. 2017).The humerus of the El-I 1 IPB is distinguished from the humeri of these forms by its much smaller size and in having a discrepant suite of morphological characters.On humeri of these phocines, the deltoid crest is shorter and terminates on the proximal shaft of the bone, its distal end does not exceed the middle part of the bone diaphysis, and the lateral epicondyle crest does not reach the distal part of the deltoid crest (Koretsky and Peters 2008;Koretsky and Ray 2008;Koretsky et al. 2014;Dewaele et al. 2017).This derived character is not observed in phocines from the Paratethyan Miocene basin and is mostly found in the Pliocene and in extant representatives of the subfamily (Koretsky 2001).Besides, the lesser tubercle in Gryphoca, Phocanella, and Batavipusa is located proximally to the head, and the head is proximodistally compressed (Koretsky and Ray 2008;Koretsky et al. 2014), while in Nanophoca the head is hemispherical (Dewaele et al. 2017).
Among the Middle and Late Miocene representatives of the subfamily Phocinae, the Eldari I phocid record reveals a significant morphological similarity with the genus Praepusa.Gadzhiev (1997) described the cranial fragment as having an anterior portion of the maxilla bones that narrows sharply and a first molar that is located labially from the upper teeth row axis.These morphological traits are also characteristic of Praepusa vindobonensis, the only representative of the genus whose cranial morphology is known (Koretsky 2001).Similarly to the genus Praepusa, the Eldari I seal mandible has a concave lingual surface and a lingually directed chin prominence.The lower premolars are tricuspids, with a well-developed main cusp and additional smaller anterior and posterior cuspids (Gadzhiev 1997).The newly obtained material also shows some morphological features which are diagnostic for the genus Praepusa (Koretsky 2001(Koretsky , 2003;;Koretsky et al. 2015).The forelimb bones of El-I 1 IPB are slender (Figure 2), the scapula neck is narrow and elongated, the deltoid crest of the humerus is in the shape of a sharp blade, and its distal end smoothly descends to the condyles.The lateral epicondyle reaches the distal part of the deltoid crest, the lesser tubercle is elongated along the bone axis, and the head ratio of width to its height is more than 0.964.Taking all the above into consideration, it is evident the remains of the Eldari I phocid belong to the genus Praepusa.
In contrast to other Paratethyan Phocinae, the genus Praepusa is characterised by its species diversity as four representatives of the genus have been described (Pr. vindobonensis, Pr. pannonica, Pr. magyaricus, and Pr.boeska).Cranial materials are known from only two species of the genus, Pr. pannonica and Pr.vindobonensis (Kretzoi 1941;Antoniuk and Koretsky 1984;Koretsky 2001).Detailed morphological comparison of the Elderi I seal cranial remains (Gadzhiev 1997) with materials of Pr. vindobonensis and Pr.pannonica revealed the features that are characteristic of the genus, as well as the significant anatomical differences between these species.The mandibular chin prominence of these species is located between p3 and p4, whereas on the Eldari I material the chin prominence is placed slightly posteriorly under the p4.The m1 alveolus of the Eldari I seal is longer than the length of the p4 alveolus, the diastema between the p4 and m1 is the smallest compared to the diastems between other teeth.On the mandibles of Pr. pannonica and Pr.vindobonensis in contrast to the Eldari I phocid, the length of the m1 alveolus is shorter than the p4 alveolus length and the length of the diastema between the p3 and p4 is smaller than the diastema between the p4 and m1.
The differences in humeral morphological structure among representatives of the genus Praepusa are not clearly expressed.The only exception is the humerus with autapomorphic traits of Pr. boeska, which has more distinct morphological features than the humeri of Pr. vindobonensis and Pr.magyaricus.Similar to these species, the humerus of El-I 1 IPB differs from the humerus of Pr. boeska, where the deltoid crest is relatively small and short, its distal end does not reach the coronoid fossa, and the deltoid crest reaches its maximum width in the middle part.The lesser tubercle is located proximally to the greater tubercle and distally from the level of the head, whereas the greater tubercle is placed below the level of the head and the lesser tubercle.The lateral epicondyle does not reach the bone diaphysis, but, unlike other Late Neogene phocines from Northern Europe, its proximal edge reaches the distal part of the deltoid crest.The reduction of the deltoid crest and partly of the lateral epicondylar crest is probably the result of an adaptation to the open basins with a lower temperature regime in contrast to the Paratethys basin.The morphology of the humerus of the Eldari I phocid is more closely resembles that of Pr. vindobonensis and Pr.magyaricus, though there are also marked differences.Divergently from these species, the intertubercular groove on the humerus of El-I 1 IPB is relatively wide and not deep, the greater tubercle is positioned at the level of the head proximal edge, and the lesser tubercle is located at the level of the proximal edge of the deltoid crest and does not reach the proximal edge of the head.There are also significant morphometrical disparities; the bones of El-I 1 IPB are half the size of the forelimb remains of other representatives of Praepusa (Figure 5; Table 1).On the proximal segments of the specimen (stylopodium and zeugopodium proximal epiphyses), the epiphyses are well fused with no apparent fusion lines.Unlike the autopodium bone, where epiphyseal fusion lines are well expressed, the epiphyseal fusion process of the phalanges is not completely ended.A similar combination is found in the recent skeletons of Pusa caspica stored at the comparative anatomy collection of the L. Davitashvili Institute of Palaeobiology.Fusion lines on the scapula, humerus, radius, and ulna (proximal epiphyses) are not preserved in adult individual specimens no.106 IPB and no.125 IBP, which is contrary to the not fully fused distal epiphyses of the radius and ulna, the metacarpal bones, and the phalangeal epiphyses.The extremely small size of the specimen El-I 1 IPB is probably a trait of sexual dimorphism, which character is defined for Monachopsis pontica, where females are a relatively smaller proportion than males (Koretsky 1987(Koretsky , 2001)).Regarding all the above, the specimen El-I 1 IPB represents a subadult female individual; accordingly, its dimensions represent the lower rates of intraspecific variation of Pr. procaspica.Based on the dimensions, it is possible to assume that the innominate bone (El-I 2 IPB) also belongs to the same individual and this is also supported by the fact that both specimens were found in the same sandstone block.In contrast to the remains of El-I 1 IPB and El-I 2 IPB, the metacarpal bones of El-I 52 IPB belong to a relatively large 'senescent' adult individual (Figure 4).Published data on the morphology and morphometry of metacarpals of the extinct phocines are very scarce, as the illustration and dimensions of metacarpals of the genus Praepusa are given only in the publication of Toula (1897, Pl. 9, fig. 20 and 21).The morphological similarity between the specimen El-I 52 BP and the drawing of Mc I, II and III of Pr. vindobonensis presented by Toula is evident.In terms of dimensions, the Eldari I (El-I 52 IPB) specimen is smaller but more robust (Figure 4; Table 2), with the only exception being the Mc I, which is longer and larger than the Mc I in Toula's figure (1897, Pl. 9, fig. 20 and 21).This difference may be a manifestation of sexual dimorphism, where males have more inflated and massive metapodials and a more elongated and robust first metacarpal than females.These metapodial characteristics are a result of the relatively large proportions and elongated limbs in males.Therefore, the El-I 52 IPB undoubtedly represents an adult male individual of the genus Praepusa.For this stage, we tentatively assign the material to Pr. cf.procaspica, since the morphological and morphometric details of the metacarpals of other species of the genus are not yet known.It is difficult to discuss the sexual attribution of the material described by Gadzhiev (1997) due to incomplete data.The remains are represented by an adult individual(s), as the lower teeth are heavily worn, and the epiphyseal fusion lines on the postcranial bones are not prominent.
According to the humeral proportions, the early and middle Sarmatian (s.l.) phocines of the Paratethys basin are represented by three morphometric groups, which are differentiated by both proportional and morphofunctional differences (Figure 5).The most massive of the group is Cryptophoca maeotica and the smallest is Monachopsis pontica.Interposed between these two groups is the third group, with some symmetry, covering mainly the interspecific variation range of Praepusa vindobonensis.The third group also includes other representatives of the genus Praepusa (Pr.magyaricus and Pr.boeska).In the third group falls the main humeral dimensions of Sarmatonectes sintsovi, which lie within the range of intraspecific variation of Pr. vindobonensis (Figure 5).Also noteworthy is the identical humeral morphological structure of Praepusa and Sarmatonectes (Koretsky 2001(Koretsky , 2003;;Koretsky et al. 2015); the humerus attributed to the latter taxon (Sarmatonectes) could be assigned to the genus Praepusa.The humerus proportions (the lower rates of intraspecific variation; Figure 5a-c) of Praepusa procaspica (El-I 1 IPB) are considerably smaller than in other species of the genus Praepusa and even smaller than the 'dwarf' forms of the subfamily Phocinae (Mo. pontica, Ba. neerlandica, and Na. vitulinoides;Koretsky 2001;Koretsky and Peters 2008;Dewaele et al. 2017).Among the materials of the subfamily Phocinae known in the scientific literature to date, the Eldari I specimen El-I 1 IPB is the smallest.
Most of the fossil phocid records of the Eastern Paratethys are known from the early and middle Sarmatian (s.l.) sediments of the northern shore of the basin (northern littoral region of the Black Sea).Little is known about seal remains found in the southern part of the basin.Only a few poorly explored fragmentary materials have been reported from the territory of the southern Caucasus (Bogacheva 1927(Bogacheva , 1938;;Gadzhiev 1959;1961;Aslanova 1965), including the recently recovered remains of Cryptophoca sp. at the Küçükçekmece locality in Turkey (Peigné 2016).The material described by Peigné (2016), like the Eldari I phocid, is characterised by its relatively small size (20% smaller than Cr.maeotica from the northern Black Sea region) and by the m1 being longer than the p4.In any case, the similarity cannot be considered a sign of a close phylogenetic relationship between these two phocids; rather, these morphological features represent adaptive convergent traits of these two contemporaneous genera (late Vallesian/ late Sarmatian) in response to the altered environment.During the early and middle Sarmatian (s.l.), the Eastern Paratethys Sea was represented by an epicontinental basin encompassing a large area (Figure 1a), which was strongly connected to the Mediterranean basin and thereby retained a high salinity water body (Popov et al. 2004;Esin et al. 2018;Palcu et al. 2021).The Volhynian and Bessarabian (early and middle Sarmatian) basins are characterised by the biodiversity of marine invertebrate and vertebrate organisms (Nevesskaia and Ilina 1986;Koiumdjieva et al. 1988;Paramonova 1994;Koretsky 2001;Koretsky andRahmat 2013, 2021;Gol'din et al. 2020;Krijgsman et al. 2020).Fundamentally different environmental conditions prevail in the Khersonian (late Sarmatian) basin.As a consequence of the tectonic activity processes and sea level drop at the end of the middle Sarmatian (Bessarabian), the connection with the Mediterranean Sea was interrupted (Steininger and Rögl 1984;Palcu et al. 2018Palcu et al. , 2021)).Since the primary water source of the Khersonian basin was freshwater rivers, the basin began desalination, and the salinity eventually was reduced (Nevesskaia et al. 1986;Paramonova 1994).During the Vallesian crisis, the warm and humid climate was replaced by a relatively dry environment (Fortelius et al. 2002(Fortelius et al. , 2003;;Shatilova et al. 2011;Zubakov 1990;Zubakov and Borzenkova 1990;Vasiliev et al. 2015), causing a sharp decrease in the basin area (Figure 1b) where the late Sarmatian (s.l.) sea level dropped 230 metres from the Bessarabian basin level (Popov et al. 2010;Palcu et al. 2018).These drastic palaeoclimatic, palaeogeographic, and palaeoecological changes in the Eastern Paratethys basin had a negative impact on the biocenosis and biodiversity of the basin, as calcareous nannoplankton vanished, and the complexes of molluscs, ostracods, and foraminifera were significantly depleted (Muskhelishvili 1980;Maisuradze 1981;Karmishina 1986;Nevesskaia et al. 1986;Nevesskaia and Ilina 1986;Paramonova 1986Paramonova , 1994;;Paramonova et al. 1986;Koiumdjieva et al. 1988;Nevesskaia 1999;Maisuradze and Koiava 2011;Radionova et al. 2012;Krijgsman et al. 2020).It also affected the vertebrate fauna of the basin by significantly reducing the diversity of ichthyofauna and marine mammals (Bazhanov et al. 1958;Mchedlidze 1976Mchedlidze , 1984Mchedlidze , 1988;;Danilchenko 1986;Gol'din and Startsev,2017).It is unlikely that such radical habitat changes did not affect the seals that inhabited the early and middle Sarmatian (s.l.) Paratethys Basin.In fact, all phocid remains found on the territory of the Black Sea northern littoral region are from the early and middle Sarmatian (s.l.) deposits, and no confirmed findings have been reported (Figure 1) from the late Sarmatian (Khersonian) sediments (Kirpichnikov 1961;Grigorescu 1976;Antoniuk and Koretsky 1984;Koretsky and Ray 1994;Koretsky 2001; Koretsky and Grigorescu 2002;Koretsky and Barnes 2006;Koretsky andRahmat 2013, 2021).The only record of phocids found in the late Sarmatian and Meotian sediments on the Kerch Peninsula were redeposited from the middle Sarmatian (Bessarabian) deposits (Bruzgin 1966;Koretsky 2001).It is reasonable to assume that in the Kersonian phocines the reduction in body size and masticatory structure alteration derived due to the changes in the basin environment and dietary differences, which is confirmed by the late Sarmatian (s.l.) contemporaneous material found in Eldari I and Küçükçekmece sites.

Conclusion
In this paper, the research and analysis of newly obtained and previously published seal material from the Late Miocene Eldari I site (South Caucasus) are provided.The results demonstrate that the remains belong to a small-sized representative of the genus Praepusa; therefore, 'Phoca' procaspica is reassigned to Praepusa procaspica.The distinctive morphological characteristics of Pr. procaspica that distinguish it from other species of the genus are established.The humeral morphometric analysis of Pr. procaspica and other Middle-Late Miocene phocines from the Paratethys Basin revealed different proportional and morphofunctional groups of the taxa.According to the morphometric comparative analysis, the Eldari I phocine is the smallest known representative of the subfamily.The extremely small size of Pr. procaspica is likely the result of adaptation to the dramatically changed environment, which occurred in the Eastern Paratethys Basin during the transitional time between the middle and late Sarmatian (Bessarabian and Khersonian).The diverse Phocinae community of the Volkhinian and Bessarabian basins of the Eastern Paratethys became diminished in the Khersonian basin as a result of the drastic palaeoecological and palaeogeographic changes.

Figure 1 .
Figure 1.Palaeogeographic reconstruction maps of the Eastern Paratethys Sarmatian Basins (after Popov et al. 2004; Palcu et al. 2021): a) the early and middle Sarmatian (Volhynian and Bessarabian) basins with indications of fossil Phocinae records; b) the late Sarmatian (Khersonian) basin with fossil Phocinae records from Eldari I and Küçükçekmece sites.The red Asterisks denote the location of the Eldari I site.Maps created using the Free and Open Source QGIS (http://qgis.osgeo.org).

Figure 3 .
Figure 3. Right innominate bone fragment of Praepusa procaspica (El-I 2 IPB) in lateral view.The scale bar is 5 cm.

Figure 4 .
Figure 4. El-I 52 IPB -a) the fossil-bearing sandstone block from the Eldari I site, b) the right carpal and metacarpal I-V bones of Praepusa cf.procaspica in dorsal view, c) the terrestrial mammal (Cervidae) metatarsal III-IV bone, d) the late Sarmatian Mactra caspia shell imprint.Scale bar is 5 cm for (a) and 2 cm for (b).