Systematic Palaeontology

Echinoidea Leske, 1778
Cidaridae Gray, 1825
Cidarinae Mortensen, 1928
Prionocidaris Agassiz, 1863

Type species. - Prionocidaris pistillaris (Lamarck, 1816), by original designation.

Range and distribution. - Lower Cretaceous (Albian) to Recent, worldwide.

Prionocidaris sp.
Figure 2.1

Description. - The fragment is 12 mm long (UNEFM-IF-001). By applying the circle perimeter equation, the test diameter was reconstructed to be 12.7 mm. The somewhat sinuous ambulacral plating is simple (unigeminate). Each plate comprises conjugate pore-pairs and distinct primary and secondary tubercles (Figure 2.2). Primary tubercles on interambulacral plates are perforated and non-crenulate (Figure 2.3). Ovate areoles are surrounded by almost uniform scrobicular tubercles. The narrow extrascrobicular zones are covered with secondary tubercles and granules. The small spine fragments embedded in the surrounding sediment are cylindrical with traces of a coarse granular ornamentation.

Remarks. - Fossils of the genus Prionocidaris are known from the Late Cretaceous to Miocene. Therefore, our Late Miocene to Pliocene specimen appears to be the youngest known fossil of this genus. Furthermore, the genus Prionocidaris shows a different geographical distribution of fossil and extent species (Mortensen 1928). Prionocidaris fossils are known from Europe and the Mediterranean as well as from the entire Caribbean. Extant species, however, are known from the Indian and the Pacific Ocean.

Stratigraphic range. - The La Vela Formation (Late Miocene to Pliocene).

Locality. - La Vela region, Falcón State, Venezuela.

Material. - Fragment showing one interambulacrum and adjacent ambulacra broken along the perradial suture on both sides, UNEFM-IF-001.

Arbacioida Gregory, 1900
Arbaciidae Gray, 1855
Arbacia Gray, 1835

Type species. - Arbacia lixula (Linnaeus, 1758), by subsequent designation of Agassiz and Clark, (1908: 67).

Range and distribution. - Miocene to Recent, Mediterranean, both coasts of Central and South America.

Arbacia punctulata (Lamarck, 1816)
Figure 3

Description. - The test measures 25 mm in diameter and 12 mm in height (UNEFM-IF-002). It is hemispherical with a flattened oral side. Throughout the whole ambulacra, trigeminate plating is visible. The pore zones become wider towards the oral surface. Tuberculation is small and irregular on the aboral surface increasing in size towards the ambitus. Mostly naked interambulacral plates stand out on the aboral surface. Imperforate and non-crenulate primary tubercles show relatively large mamelons with poorly defined areoles. The inner interambulacral tubercles on the aboral side are of the same size as those in the adradial series. On the badly preserved oral side, a rather large peristome is recognizable.

Remarks. - Arbacia punctulata is a well known species of Pliocene age. It is distributed throughout the western Atlantic seaboard and the whole Caribbean. It is very similar to the two Pacific coast species A. spatuligera (Valenciennes, 1846) and A. stellata (Blainville, 1825). Aside from coloration and spine morphology, which are not preserved, A. punctulata appears not to have any morphological differences to A. stellata. The difference to A. spatuligera is more obvious since A. punctulata has tubercles of equal size both on the interambulacra and the adradial series in contrast to its Pacific coast relative with smaller tubercles on the inner interambulacra (Mortensen 1935).

Stratigraphic range. - Cocuiza Member of the San Gregorio Formation (Late Pliocene to Early Pleistocene); Pliocene to Recent.

Locality. - Cocuiza West locality, Codore Adentro region, Falcón State, Venezuela.

Spatial distribution. - The western Atlantic seaboard, the whole Caribbean.

Material. - One rather poorly preserved specimen (UNEFM-IF-002).

Echinoida Troschel, 1872
Toxopneustidae Troschel, 1872
Lytechinus Agassiz, 1863

Type species. - Lytechinus variegatus Lamarck, 1816, by monotypy.

Range and distribution. - Eocene (Scoliechinus), Oligocene to Recent, both coasts of the Americas, but mainly in the Gulf of California and the Caribbean.

Lytechinus cf. euerces Clark, 1912
Figure 4.1

Description. - The diameter of the best preserved test measures 16 mm (UNEFM-IF-004). Each ambulacral trigeminate compound plate has both primary and secondary tubercles (Figure 4.2). The latter are small and irregularly dispersed. The conjugate pore pairs form oblique lines of three. Interambulacral plates carry a rather small, non-crenulate primary tubercle and several, well-spaced, slightly smaller secondary tubercles (Figure 4.3). The rest of the tuberculation is small and irregularly distributed. The peristome margin is defined by sharp and distinct buccal notches.

Remarks. - Although the material's preservation is not outstanding, the prominent buccal notches are sufficiently well preserved to assign the material to the family Toxopneustidae. Since the here described specimens do not preserve the peristome plating, which is usually applied for the identification of the genus Lytechinus, pattern and tuberculation of both ambulacral and interambulacral plates were used for the determination. Recent L. euerces are known from the Caribbean from the Gulf of Mexico to Barbados (Smith 2005).

Stratigraphic range. - The La Vela Formation (the Late Miocene to the Pliocene).

Locality. - La Vela region, Falcón State, Venezuela.

Spatial distribution. - Gulf of Mexico to north-west of Tortuga and to Barbados.

Material. - Three specimens: one is compressed UNEFM-IF-003, one has a rather well preserved oral side UNEFM-IF-004 and one shows a rather damaged surface UNEFM-IF-005.

Clypeasteroida Agassiz, 1835
Clypeasteridae Agassiz, 1835
Clypeaster Lamarck, 1801.

Type species. - Clypeaster rosaceus Linnaeus, 1758, by original designation.

Range and distribution. - Late Eocene to Recent, worldwide in tropical to temperate regions.

Clypeaster rosaceus Linnaeus, 1758
Figure 5.1

Description. - The test is sturdy due to a double-walled margin created by inner peripheral partitioning (UNEFM-IF-006). The oral surface is concave. The petals become wider distally. On the ridges between the pore pairs 8 to 9, primary tubercles are aligned in a regular series (Figure 5.1). The furrows between primary tubercle series are narrow but fairly deep and sharp. The interambulacral tuberculation is conspicuous (primary tubercle diameter 0.5 mm) and irregularly arranged.

Remarks. - The genus Clypeaster is distributed throughout tropical to temperate regions from the Late Eocene to today. Clypeaster represents a paraphyletic or even a polyphyletic genus with more than thirty species (Mortensen 1948). A detailed revision and subdivision of this genus is needed. Clypeaster rosaceus's test is characteristic for its highly rounded but not limited edge and gradual transition towards the moderately high, rounded apex. It is a common species in shallow waters, down to depth of 50 m, of the West Atlantic and Caribbean coasts from South Carolina to Venezuela.

Stratigraphic range. - The La Vela Formation (the Late Miocene to the Pliocene); Plio-Pleistocene to Recent.

Locality. - La Vela region, Falcón State, Venezuela.

Spatial distribution. - The Caribbean and the south-eastern USA.

Material. - Three fragments with a rather well preserved surface: UNEFM-IF-006, UNEFM-IF-007, UNEFM-IF-008.

Clypeaster subdepressus (Gray, 1825)
Figure 5.3

Description. - The test measures more than 100 mm in length and displays a subpentagonal outline with a rounded margin (UNEFM-IF-009). The test shows no indication of convergence on the oral side. The apical disc is somewhat distorted but the presence of five gonopores is clearly visible. Both the anterior and posterior pairs of petals are well-developed and almost closed distally. The anterior petal is damaged anteriorly; therefore, it is not clear if it is completely closed. All petals are slightly inflated and show a leaf-shaped form. The ridge between the pore pairs carries 13 to 15 regularly arranged primary tubercles (Figure 5.2). Interambulacral tuberculation is rather small (primary tubercle-diameter 0.25 mm) and irregularly arranged.

Remarks. - Due to the exceedingly high number of synonyms and misidentifications, the description of C. subdepressus remained dubious until Mortensen (1948) published a comprehensive revision. Due to the above mentioned reasons, the spatial distribution of C. subdepressus is uncertain, but this species appears to be distributed throughout the entire Caribbean from Florida to the Atlantic coast of Brazil.

The key trait that distinguishes C. subdepressus from other similar Clypeaster species is the high number of primary tubercles (13-15) on ridges between the pore-pairs. This feature is unfortunately not referred to in Kier's (1963a) description of Florida's C. sunnilandensis Kier, 1963, for which he states that its only difference to C. subdepressus is an opened anterior (III.) petal. Since the anterior petal in our specimen is damaged, it is hard to verify this. However, due to the spatial distribution of both species, we are confident to assign our material to C. subdepressus.

Stratigraphic range. - The La Vela Formation (the Late Miocene to the Pliocene); Pliocene to Recent.

Locality. - La Vela region, Falcón State, Venezuela.

Spatial distribution. - The Caribbean from Florida to northern Brazil.

Material. - The best preserved specimen has a well preserved aboral side UNEFM-IF-009. The additional specimens represent fragments mostly showing parts of the petals (UNEFM-IF-010, UNEFM-IF-011, UNEFM-IF-012, UNEFM-IF-013).

Mellitidae Stephanini, 1912
Mellitella Duncan, 1889

Type species. - Encope stokesii Agassiz, 1841, by subsequent designation.

Range and distribution. - Miocene to Recent, East Pacific and Caribbean.

Mellitella falconensis Cooke, 1961
Figure 6.1

Description. - The test sizes range between 30 and 50 mm in diameter. The horizontal outline of the test is subcircular with a posterior truncation. Five ambulacral notches on different specimens show different degrees of closure. The anal lunule is small and situated near the posterior margin, i.e., it always lies completely behind the posterior petals UNEFM-IF-016, (Figure 6.1). On the apical surface, five gonopores are clearly visible, as well as weakly bowed petals that are converging distally but remain opened. All petals are rather short and approximately half as wide as long UNEFM-IF-016. The periproct is situated midway between the peristome and the margin and does not reach the fifth basicoronal interambulacral plate UNEFM-IF-018. The peristome is small, central and pentagonal. Conspicuous food grooves are bifurcating immediately distal to the basicoronal plates and are converging around the ambulacral notches UNEFM-IF-018.

Remarks. - The literature is ambiguous in defining the taxon Mellitella; by some authors, it is defined as an independent genus (Smith 2005; Mooi 1989) and by others as a subgenus (Mortensen 1948; Cooke 1961; Schultz 2006) within the genus Encope. These two taxa share significant taxonomic traits, such as five gonopores, five well-marked ambulacral notches or lunules and a periproct that does not intent the basicoronal plates in the fifth interambulacrum. Mellitella's simpler inner structure and more fragile separation of the intestine tract from the central cavity are the most distinctive features (Mortensen 1948). To study these and other features we made a tomography of UNEFM-IF-021 (Figure 6.2). However, the small anal lunule is situated near the posterior margin that always lies completely behind the posterior petals; this is, for the analysis of our material, the most important feature that distinguishes Mellitella from Encope.

Mellitella includes, besides M. falconensis, the two species M.stokesii (Recent) and M.angelensis Durham, 1950 (Pliocene). These are, however, known from the Pacific coast only (Smith 2005). The Chiguaje formation (Miocene) and the San Gregorio Formation (Pliocene) in Venezuela appear to be the only known localities where M. falconensis is found.

Cooke (1961) mentioned that ambulacral notches are not yet closed in smaller specimens. During the examination of this new material, however, no such correlation between size and notch closure could be found. During the examination of this new material, however, no such correlation between size and notch closure could be found, consistent with the material of M. falconensis in the collection of the Natural History Museum Basel that also does not show this ontogenetic closure of the ambulacral notches. It appears likely that more factors (environment, injuries) other than just the ontogenetic stage have an influence on the degree of notch closure.

Stratigraphic range. - Cocuiza Member of the San Gregorio Formation (the Late Pliocene to the Early Pleistocene).

Locality. - Cocuiza West und Cocuiza East locality, Codore Adentro region, Falcón State, Venezuela.

Spatial distribution. - Falcón State, Venezuela.

Material. - The fossil material includes eleven fragments of varying preservation quality (UNEFM-IF-014 to -024).

Encope Agassiz, 1841

Type species. - Encope grandis Agassiz, 1841, by original designation.

Range and distribution. - Early Miocene to Recent, both coasts of Central and South America but mainly in the Gulf of California and Florida.

Encope cf. emarginata (Leske, 1778)
Figure 6.3

Description. - This species is characterized by its long and somewhat irregular anal lunule. The anal lunule incises deeply between the posterior petals (UNEFM-IF-029). The petal is slightly curved and converges distally but remains open. The food grooves are bifurcating and become highly branched distally. Internal structures are sponge-like, i.e., the internal buttressing is extremely dense.

Remarks. - Encope emarginata is widely distributed from the Pliocene until today in the entire Caribbean, from the intertidal zone to a depth of about 50 m. The length of the anal lunule and the lunule/test length-ratio were used to estimate the size of the actual specimen. The lunule/test length-ratio was calculated using figure 658 from Schultz (2006). The estimated length is 115 mm which is within the range of intraspecific variability known from E. emarginata (Schultz 2006).

Stratigraphic range. - Cocuiza Member of the San Gregorio Formation (Late Pliocene to Early Pleistocene); Pliocene to Recent.

Locality. - Concuiza West locality, Codore Adentro region, Falcón State, Venezuela.

Spatial distribution. - The Caribbean, south-eastern USA and north-eastern South America.

Material. - One poorly preserved fragment showing the fifth ambulacra and the left part of the anal lunule, probably Recent (UNEFM-IF-029).

Encope secoensis Cooke, 1961
Figure 6.4

Description. - The diameter of the completely preserved test amounts to 62 mm (UNEFM-IF-025). The test shows a discoidal shape with a flat oral side and the highest point being located anteriorly. Test margin is interrupted by five well-marked ambulacral notches that show the tendency to close by bending their edges toward each other. The anal lunule is elongated, narrow and extends between the distal tips of the posterior petals. The apical disc is star-shaped showing five gonopores. All petals are open distally, although the poriferous zones are approaching each other. Posterior petals are somewhat longer than the anterior petals. The periproct is elongated and situated closer to the anal lunule than to the peristome, although it does not approach the basicoronal plates of the fifth interambulacrum. The peristome is situated orally, directly beneath the apical disc on the aboral surface. The food grooves are branching immediately behind the basicoronal plates and converging distally around the ambulacral notches.

Remarks. - Like Melitella falconensis, E. secoensis is also known only from the Chiguaje formation (Miocene) and the San Gregorio Formation (Pliocene) in Venezuela. Because of the thin test margin, incompletely closed ambulacral notches, the food groove shape and the elongated narrow anal lunule, E. secoensis somewhat resembles E. michelini Agassiz, 1841. Nevertheless, the test of E. secoensis has its highest point anterior to the centre which distinguishes it from E. michelini. An elongated periproct, situated closer to the anal lunule than to the peristome, is an additional diagnostic feature of E. secoensis. To document the inner structure of E. secoensis, we took an x-ray image (Figure 6.4) for the first time.

Stratigraphic range. - Cocuiza Member of the San Gregorio Formation (Late Pliocene to Early Pleistocene).

Locality. - Cocuiza East locality, Codore Adentro region, Falcón State, Venezuela.

Spatial distribution. - Falcón State, Venezuela.

Material. - One well-preserved specimen (UNEFM-IF-025) and three rather well-preserved fragments, all darker coloured (UNEFM-IF-026, UNEFM-IF-027, UNEFM-IF-028).

Spatangoida Agassiz, 1840
Prenasteridae Lambert, 1905
Agassizia Valenciennes, in Agassiz and Desor, 1847

Type species. - Agassizia scrobiculata Valenciennes in Agassiz and Desor, 1847, by original designation.

Range and distribution. -Middle Eocene to Recent, mainly Caribbean.

Agassizia excentrica Agassiz, 1869
Figure 7.1

Description. - The longest diameter of the ovate test without anterior sulcus is 23 mm long and the shortest 21 mm (UNEFM-IF-030). The long, weakly sunken anterior petal is broadening anteriorly and carries only one row of pore pairs (Figure 7.2). The posterior column of the anterior petal pair is developed whereas the anterior series is inconspicuous. All petals are slightly depressed. The posterior petals are short, just about 1/3 of the length of the anterior ones, and show a less developed upper part of the anterior series of pore pairs (Figure 7.2). The well-developed peripetalous fasciole is situated very low anteriorly, passing three plates below the end of the anterior petals, and rises steeply towards the end of the posterior petals forming a parabolic trace. Behind the anterior pair petals, the peripetalous fasciole is touching the lateroanal fasciole that is running towards the periproct and passes beneath it. Due to poor preservation of the oral surface, one can only suspect the position of a D-shaped peristome.

Remarks. - Agassizia excentrica is distributed throughout the entire Caribbean. The reduced pores of anterior series of pore pairs on the posterior petals are the main difference to the pacific species A. scrobiculata Valenciennes, 1846. The posterior petal in our specimen has fewer plates with reduced pores in the outer column than shown in Mortensen (1951, figure 157).

Stratigraphic range. - Cocuiza Member of the San Gregorio Formation (Late Pliocene to Early Pleistocene); Recent.

Locality. - Cocuiza West locality, Codore Adentro region, Falcón State, Venezuela.

Spatial distribution. - The Caribbean.

Material. - One specimen which is missing the first and second petals UNEFM-IF-030, and a second specimen showing just one half of the test with the lateroanal fasciole UNEFM-IF-031.

Schizasteridae Lambert, 1905
Moira Agassiz, 1872

Type species. - Moira atropos (Lamarck, 1816), by ICZN designation, 1948.

Range and distribution. -Miocene to Recent, Indo-Pacific, Caribbean, western Atlantic.

Moira atropos (Lamarck, 1816)
Figure 8

Description. - The test lengths range from about 20 to 40 mm and the maximum test height varies between 10 and 15 mm. The test is ovate in outline with an anterior sulcus and vertically truncated at its posterior end (UNEFM-IF-032). The aboral test side is highly vaulted in contrast to the oral side that is flattened. The aboral surface of the test is characterized by deeply sunken ambulacra (Figure 8.1). The anterior ambulacrum is the deepest, but it is shallowing near the ambitus. The posterior petal pair is half as long as the anterior petal pair. The periproct is situated high up on the vertical posterior end (Figure 8.2). The peripetalous and lateral fascioles are well developed. The kidney-shaped peristome is wider than long and is situated close to the anterior end. The wide and short labial plate is prominent but not extending posteriorly beyond the first ambulacral plates (Figure 8.3). The sternal plates are long and slightly widened posteriorly (2/3 as broad as long). Tuberculation on both aboral and oral sides is uniform and dense, but somewhat more prominent on the oral side.

Remarks. - Moira is easily recognizable by its deep ambulacra. These ambulacra appear to be an adaptation to an infaunal mode of life, allowing water to flow through the ambulacra which are kept free of sediment by spines and tube feet. Mortensen (1951) emphasized that most spatangoids, although lacking deep ambulacra, may well have lived infaunally, independent to some extent of the sediment composition.

Due to the vertically truncated shape of the posterior end of the test, M. clotho Michelin, 1855 resembles M. atropos. However, in contrast to M. atropos, M. clotho's sternum is strongly widened posteriorly: it is 3/4 as broad as long. Moira atropos is known from the east coast of the Americas, from Massachusetts, USA to Sao Paulo, Brazil.

Stratigraphic range. - Cocuiza Member of the San Gregorio Formation (Late Pliocene to Early Pleistocene); Recent.

Locality. - Cocuiza West locality, Codore Adentro region, Falcón State, Venezuela.

Spatial distribution. - The east American coast from North Carolina to Brazil, the Caribbean.

Material. - Four well-preserved specimens: UNEFM-IF-032 to -035.