Fossil Echinoids

FIRST RECORD OF THE GENUS GAGARIA (ECHINOIDEA) FROM THE EOCENE OF ITALY.
Gagaria Duncan, 1889 is a rare echinoid genus known from latest Palaeocene to Oligocene of the Indo-Pakistan Region and western Africa. It is present, though very rare, also in the Eocene of the Mediterranean (Spain and France). The systematic of Gagaria is not well resolved yet and the genus is placed in a temporary family, the “Triplacidiis”. The main diagnostic character of this genus, consisting of the composition of the ambulacral plates, is visible only in rare well preserved specimens. As a consequence the generic placement of a part of the species earlier attributed to Gagaria remains uncertain. Two well preserved specimens from the middle Eocene of northern Italy are attributed to Gagaria, on the basis of the ambulacra plates, compounded in acrosaleniid style, with two elements bound by the primary tubercle, both extending to the perradial suture. Between these compound plates there are simple plates with only secondary tubercles. Other distinctive characters are: pore-zones straight and not widened at the peristome, primary tubercles imperforate and crenulate forming a regular series in each column in both areas, secondary tubercles not forming complete longitudinal series. The apical system with only ocular plate I insert points to G. venustula (Duncan & Sladen, 1884), the type species.
The material under study was collected from middle Eocene (early Lutetian) volcanoclastic tuffites of cava Albanello (province of Vicenza). The volcanodetritic beds are indicative of instant events of mass transport. A shallow, warm water palaeoenvironment was prospected for the tuffites and hyaloclastites of the Val di Chiampo.
The material under study is compared with Cyphosoma superbum Dames, 1877, another rare taxon belonging to the “Triplacidiids”, from the Eocene of San Giovanni Ilarione (Vicenza). It is represented by a sole and incomplete test, whose generic placement remains uncertain. It is distinguished from the examined specimens by higher test, subconic profile, more conspicuous and more regularly disposed secondary tubercles in the interambulacra, also adapically, and smaller primary tubercles.
This is the first record from the Mediterranean of the type species, G. venustula, which was so far known with certainty only from the Indo-Pakistan area.

A review of Monostychia, a stratigraphically important clypeasteroid echinoid genus in southern Australian Oligocene/Miocene strata, reveals uncertainty in relation to morphological features used in taxonomy. The result is that the exact systematic position of the genus remains unresolved at subfamily level. Monostychia and its type species, M. australis, are redescribed. Monostychia australis is restricted to the lower to middle Miocene Glenforslan Formation of the Murray Basin. Three other species currently within Monostychia, M. etheridgei, M. loveni and M. elongata,
are discussed. Although it is concluded that M. etheridgei belongs in the genus and is a distinct species, the taxonomic position of M. loveni is
questioned, and the validity of M. elongata as a separate species from M. australis remains uncertain. This work lays the foundation for further revisions of Monostychia with an expectation that such work will provide the basis for character determination that may be useful across other echinoid taxa.

The regular echinoid Placentinechinus davolii gen. et sp. nov. is described from eight Early Pleistocene (Gelasian–Calabrian) sites in north and south Italy. It is the most recent record known for the family Temnopleuridae in the European domain and the first in the Mediterranean area. A review of temnopleurid palaeobiogeography, and morphological comparisons, suggest that P. davolii was derived from a marsupiate brooder that lived in the north-east Atlantic during Messinian–middle Gelasian time. This indicates a brooding reproductive strategy for P. davolii, although it does not bear any evidence of a marsupium. The stratigraphy and climatic setting inferred for the study sites indicate that Placentinechinus represents a significant southward shift of the European Temnopleuridae, triggered by a progressive cooling that changed the Mediterranean climate from tropical to subtropical-temperate. A further climatic deterioration, perhaps that at about 0.8 Ma with the onset of the 100 kyr-controlled Ice Ages, caused its extinction. The palaeoecology of Placentinechinus, as deduced from palaeoenvironmental reconstructions of the study sites, indicates that it lived in shoreface to shallow offshore, moderately agitated waters, often together with the scallop-polychaete Aequipecten-Ditrupa association. It tolerated more or less marked conditions of turbidity, but flourished in trophically well-structured palaeocommunities. The main morphological characters distinguishing Placentinechinus are the very depressed test and the extremely large apical opening, up to 82% of the test diameter, which is so far the largest known for an adult echinacean echinoid. The statistically exhaustive morphometric data collected from more than 100 Placentinechinus tests indicate that inferring sexual dimorphism for Temnopleuridea echinoids based only on the apical disc width could be misleading. For P. davolii, both climate and environmental stability, in terms of sedimentation rate and nutrient supply, may have been concurrent drivers of its evolutionary history.

Gauthieria mosae is recorded for the first time from upper Campanian (Belemnitella minor/Nostoceras polyplocum Zone) strata at the Teutonia Nord quarry in the Hannover area (northwest Germany), with two specimens available. This species was previously known only from the lower upper Campanian (basiplana/spiniger Zone and higher) of the province of Liège, northeast Belgium. In addition, a specimen of Gauthieria aff. pseudoradiata, from the B. minor/N. polyplocum Zone as well at the Teutonia Nord quarry, is illustrated and discussed in an attempt to elucidate the confused taxonomy of this form.

Palaeontological evidences of autochthonous deep-water echinoids are so rare that the well-preserved assemblage herein described from the Plio-Pleistocene of Capo Milazzo (NE Sicily) provide an important opportunity to investigate the biodiversity of the bathyal echinoids in the Mediterranean late Cenozoic. The low diversity fauna studied is dominated by Cidaris margaritifera, Histocidaris sicula and Stirechinus scillae, which are species closely related to Recent echinoids today confined to the western Atlantic deep bottoms. The echinoid assemblages of Capo Milazzo and of the Plio-Pleistocene Argille Azzurre Formation (Italy) share a number of species, most of which are known also from shallow water Plio-Pleistocene deposits and the present-day Mediterranean; C. margaritifera is the only strictly bathyal echinoid that occurs in both formations. The palaeoecological study of these echinoids indicates an epibenthic way of life on muddy bottoms, in deep waters with psychrospheric conditions. The following species from the Argille Azzurre are interpreted as strictly bathyal: Histocidaris rosaria, Schizaster braidensis and Schizaster ovatus (transferred into the genus Holanthus). The modern Mediterranean (impoverished) deep-water echinoid assemblage has north-eastern Atlantic affinities and, with the exception of Holanthus expergitus, all the Mediterranean species found at bathyal depth are eurybathic, as they live also in shelf settings. In contrast, the bathyal echinoids of Capo Milazzo show strongest affinities with strictly deep-water western Atlantic species, particularly those of the Caribbean area. They vanished from the Mediterranean during the Quaternary due to the loss of psychrospheric conditions. Based on the Punta Mazza section, dated by nannofossils and data from literature, their stratigraphic range at Capo Milazzo is late Piacenzian-Calabrian.

ABSTRACT - A new species of the genus Faorina Gray, 1851 (Echinoidea, Pericosmidae) from the early Miocene of Sardinia, F. maullui sp. nov., is described. This is the first fossil evidence of Faorina and the first record from the Mediterranean area. The new species differs from the Recent F. chinensis Gray, 1851, so far considered to be the only valid species of the genus, in having a depressed test, with oblique posterior face and thinner margin, a different pathway of the peripetalous fasciole and larger periproct. The diagnostic characters stated in the literature to distinguish Faorina are discussed on the basis of the new material under study, and the meridoplacous structure in the interambulacrum 1 adorally is herein considered to be the only safe feature to distinguish Faorina from the closely related genus Pericosmus L. Agassiz, in L. Agassiz & Desor, 1847. Three species from the Miocene of Italy, originally attributed in the literature to the genus Pericosmus, are transferred into Faorina.

In this paper we present the first record of well preserved specimens of Gitolampas subrotundus (Cotteau, 1856) from the Late Paleocene of Iran (Jorasán Razaví county, northeast Iran). the detailed biostratigraphic and calcareous nannofossils investigations were carried out on a stratigraphic section in Chehel Formation. this study extends the palaeogeographical distribution of Late Paleocene echinids along the northern tethyan margins. the investigated fossiliferous section is compared with coeval strata from other european regions.

The genus Schizechinus Pomel, 1869 (Echinoidea) in the Pleistocene of Emilia (Northern Italy).
Well preserved material from the Gelasian and Calabrian of Emilia enables to complete the description of Schizechinus serialis (Pomel, 1887), to clearly define its variability range and association with the other species attributed to this genus. The taxonomy of the genus Schizechinus is largely unresolved due to the lack of clear distinctive characteristics at the species level and to the uncertainty regarding the type species (see Kroh & Smith, 2006 for an overview). The study of a large number (57) of complete specimens from Emilia shows that the morphological characters traditionally utilised in the taxonomy of this genus (regarding the shape of the test and the main tubercles arrangement) are very variable. Some of them change also during the growth of the echinoid (see Tab. 2): this is also the case with the number of the main tubercles series, considered as a main distinguishing feature in earlier works dealing with this genus. Consequently, it is necessary to study large samples and compare similar-sized specimens attributed to different species. Additionally, in thin-shelled regular echinoids (such as Schizechinus) a small amount of deformation is always present even in the best preserved specimens, thus preventing the taking of exact measures above all of H, Da and Dp (see the abbreviation list). Some morphological features are less affected by this uncertainty and turned out to be more reliable for the taxonomic discussion: in particular, the shape-ratios regarding the main tubercles (Wt) and the plates at the ambitus (Wp), and the depth of the gill-slits (Lf).
Sixteen species have been attributed to Schizechinus through published literature, however at the current state of knowledge only four of them are here considered as well defined: S. duciei (Wright, 1855), from the Late Miocene of Malta, S. serresii (Desor, 1856), Burdigalian of France, S. hungaricus (Laube, 1869), Langhian-Serravallian of Austria and S. pentagonus Kier, 1972, Miocene of Saudi Arabia and Iran. The last three species have been described by modern methods (Kroh & Smith, 2006, Kroh, 2005 and Kier, 1972, respectively). S. duciei is known in the literature only by 3 specimens: the holotype, well illustrated in Smith & Kroh (2011), and 2 topotypic specimens, described by Stefanini (1908) and Cottreau (1913), respectively. A group of topotipic specimens available for this study enables a better knowledge of the morphological variability in this species; the inedited material from the Maltese islands examined in this work originated from both the Greensand and the Upper Coralline Limestone Formations (Tortonian to Messinian).
S. serialis is distinguished from the congeners above all by its larger size (test diameter up to 101 mm) and the main tubercles (including the primary tubercles and the similarly-sized secondaries), which are rather small in proportion to the plate size (corresponding to low values of the Wt ratio) and form regular and homogeneous vertical and horizontal series. However, small similar-sized specimens (D=40-50 mm) attributed to S. serialis, S. hungaricus and S. duciei look apparently similar and have the same number of main tubercles at the ambitus. In this case it is necessary to utilize biometric data to separate them:
- S. duciei differs from S. serialis by its smaller size (D=47-56 mm), flatter test profile (mean H= H=47.3.%D, H=40%D in the holotype, against 46-69%D) and shallower gill-slits (mean Lf=2.2%D instead of 3-4.5%D). Additionally, in S. duciei there are zigzagging ridges between the pore pairs (Wright, 1855, pl. 4, fig. 2e) and the pore areas are less depressed.
- S. serresii has a small test (D≈40 mm), smaller gill slits (Kroh & Smith, 2006, figs. 1 C,E) and much larger tubercles in the interambulacral plates at the ambitus (mean Wt=0,71; Kroh & Smith, 2006, figs. 2 I,H).
- S. hungaricus is distinguished by larger main tubercles [mean Wt=0.70 after Kroh (2005), 0.48 in S. serialis], lower interambulacral plates at the ambitus (Wp≈20%, instead of Wp=27%), shallower gill-slits (Lf≈2.5%D, against 3-4.5%D) with less marked margins; additionally the epiphyses have always a characteristic and well developed tooth support in the distal part (Pl. 4, fig. 2).
- S. pentagonus is a small-sized species (D=22-42.7 mm), well distinguished from its congeners by its subpentagonal outline and the larger ambulacral areas at the ambitus (mean Wa=0.70, instead of 0.51). The occurrence in the perradial area of the ambulacra of small zones deprived of the main tubercles, considered by Kier (1972, tav. 55, fig. 4) as another distinctive character of this species, is occasionally present also in S. duciei (Pl. 6, fig. 3b) and S. serialis. S. pentagonus differs from S. serialis also by larger main tubercles (Wt=0.63, against 0.48) and slightly deeper gill-slits (Lf=4.5-5%D, 3-4.5%D in S. serialis).

The first Sicilian record of the sand dollar Amphiope is reported on the basis of the occurrence of the species A. bioculata (des Moulins, 1837), recovered from a previously unreported sandy deposit cropping out near Case Genna (western Sicily). The best preserved tests are described and compared with similar congeners. Taphonomic and palaeoecological observations on the A. bioculata-thaphocenoses, and granulometric characterizations indicate that the sand dollar-bearing deposit formed in very shallow, nearshore environments subjected to bottom current. This deposit, if considered as a subunit of the deltaic upper Tortonian-lower Messinian “Molassa” of the Terravecchia Formation, would have a late Miocene age (upper Tortonian). In this case the Mediterranean distribution of A. bioculata, previously known from the Aquitanian to the lower Tortonian, should be extended to the upper part of the latter stage.