Poeyana 514: e06,  January-December  2023, ISSN: 2410-7492
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ARTÍCULO ORIGINAL

Description of two early Middle Eocene marine fish from eastern Cuba

Descripción de dos peces marinos del Eoceno Medio temprano de Cuba oriental


iDJohanset Orihuela1Department of Earth and Environment (Geosciences), Florida International University, Miami, Florida 33199, USA,

iDYasmani Ceballos Izquierdo2Independent researcher. Calle 40, #2702 e/27 y 29, Madruga, Mayabeque, Cuba.*✉:yasmaniceballos@gmail.com

iDEdelis Figueredo Garcés3Museo de Historia Natural “Carlos de la Torre y Huerta”, Holguín, Cuba.


1Department of Earth and Environment (Geosciences), Florida International University, Miami, Florida 33199, USA,

2Independent researcher. Calle 40, #2702 e/27 y 29, Madruga, Mayabeque, Cuba.

3Museo de Historia Natural “Carlos de la Torre y Huerta”, Holguín, Cuba.

 

*Author for correspondence: yasmaniceballos@gmail.com

Abstract

The ichthyofauna from the Cenozoic of the Caribbean is mostly known from fossil sharks and rays, and a reduced number of bony fishes. Most of these fossils were collected from Neogene deposits, whereas those of Paleogene age are rare. Here we report and describe two early Middle Eocene ray-finned fish (Teleostei) from vulcano-sedimentary deposits of the El Caney Formation of Eastern Cuba. The extraordinary preservation of the fossils, which includes the soft tissue outline of the specimens, allow for a unique opportunity to study, and approximate their classification. Morphological characteristics and preliminary taxonomic analysis suggest that one of these specimens belongs to the family Percopsidae while the other exhibits affinities to either the Lutjanidae or Cichlidae families. These two specimens are the oldest known members of their respective families in the Antillean region, and they add significantly to our understanding of the Eocene marine vertebrates and aquatic ecosystems of the Caribbean.

Keywords: 
Cichlidae, Cuba, Eocene, Lutjanidae, Percopsidae
Resumen

La ictiofauna del Cenozoico del Caribe es conocida principalmente por tiburones y rayas fósiles, y un número reducido de peces óseos. La mayoría de estos fósiles se han colectado en depósitos del Neógeno, mientras que aquellos de edad Paleógeno son raros. Aquí informamos y describimos dos peces del Eoceno Medio temprano de depósitos vulcano-sedimentarios de la Formación El Caney de Cuba oriental. La extraordinaria preservación de los fósiles, que incluye el contorno de tejido blando de los especímenes, ofrece una oportunidad única para estudiar y aproximar su clasificación. Las características morfológicas y el análisis taxonómico preliminar sugieren que uno de estos ejemplares pertenece a la familia Percopsidae, mientras que el otro muestra afinidades con las familias Lutjanidae o Cichlidae. Estos dos ejemplares son los miembros más antiguos conocidos de sus respectivas familias en la región antillana, y contribuyen significativamente a nuestra comprensión de los vertebrados marinos del Eoceno y los ecosistemas acuáticos del Caribe.

Palabras clave: 
Cichlidae, Cuba, Eoceno, Lutjanidae, Percopsidae

Received: 20/7/2023; Accepted: 02/9/2023

Conflict of interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Author contributions: Writing review and editing: J. Orihuela, Y. Ceballos-Izquierdo. Writing- original draft: J. Orihuela, Y. Ceballos-Izquierdo. Methodology: J. Orihuela, Y. Ceballos-Izquierdo. Investigation: J. Orihuela, Y. Ceballos-Izquierdo, E. Figueredo-Garcés. Formal analysis: J. Orihuela, Y. Ceballos-Izquierdo. Data curation: E. Figueredo-Garcés. Conceptualization: E. Figueredo-Garcés.

This article is under license Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

CONTENT

Introduction

 ⌅

The Eocene epoch, a time interval spanning from approximately 56 to 33.9 million years ago, represents a pivotal period in Earth’s history, characterized by significant transformative climatic changes and the consequent evolution of diverse vertebrate lineages (Cramwinckel et al., 2018Cramwinckel, M. J., Huber, M., Kocken, I.J. et al. (2018). Synchronous tropical and polar temperature evolution in the Eocene. Nature, 559: 382-386. ). As the world transitioned from the Paleocene, marked by the recovery from the Cretaceous-Paleogene extinction event, the Eocene witnessed the rise of many modern mammalian orders, the diversification of birds, and fishes, and the evolution of the first large marine mammals. But even while the Eocene vertebrate fossil record has been extensively studied in regions such as North America, Europe, and Asia, the Caribbean, and particularly Cuba, remains enigmatic primarily because of its limited or scant marine vertebrate fossil record.

So far, the Cuban Eocene vertebrate material includes sharks (Iturralde-Vinent et al., 1996Iturralde-Vinent, M., Hubbell, G., and Rojas-Consuegra, R. (1996). Catalogue of Cuban fossil Eslamobranchii (Paleocene-Pliocene) and paleogeographic implications of their Lower to Middle Miocene occurrence. Journal of the Geological Society of Jamaica, 31, 7-21.) manta ray teeth (Viñola-López et al., in press), and other unidentified specimens. In this context, the report of two complete fish specimens from Eocene strata of eastern Cuba represents a significant and rare addition to the island’s paleontological record.

The two specimens were collected from a quarry located in the foothills of the Sierra Maestra, near Loma Pimienta, approximately 24 km from the coast 18 km from Campechuela (Granma province), and about 500 feet above sea level. They were discovered by quarry workers who informally named them “biajaca” (Cuban cichlid) and “robalo” (snook). On February 17, 1961, researchers Eduardo Solano Osorio and Milton Pino donated the specimens to the former Museo Guamá, and at the end of the ‘60s, the specimens became part of the new Museo de Historia Natural Carlos de la Torre y Huerta (Holguín province, eastern Cuba). However, the fossil material remained neglected for decades, until geologist and paleontologist Manuel Iturralde-Vinent and geologist Carl Bowin visited the museum collection and photographed the material. Consequently, Iturralde-Vinent (2004Iturralde-Vinent, M. (2004). Origen y evolución del Caribe y sus biotas marinas y terrestres. Editorial Centro Nacional de Información Geológica, CD-Rom. ISBN: 959-7117-14-2., 2009)Iturralde-Vinent, M. (2009). Formación del Caribe y de Cuba. In: Iturralde-Vinent, M., (Ed.) Geología de Cuba Para Todos. Editorial Científico-Técnica, Instituto del Libro, La Habana. illustrated these specimens highlighting their importance for future research.

This paper aims to describe these two fish specimens and evaluate their biogeographic implications while emphasizing the challenges and opportunities presented by the scant Eocene fossil record of the island. These specimens not only provide insight into the aquatic ecosystems of the Eocene of Cuba but also represent new records of marine vertebrate fossils in the region. The identification and description of these two previously unidentified fish specimens contribute to our knowledge of circum-Caribbean marine paleoecosystems, as well as the evolution and biogeography of these organisms.

Materials and methods

 ⌅

The specimens studied here are housed in the collections of the Museo de Historia Natural Carlos de la Torre y Huerta (MHNCT) under the number MHNCT 12-23. Since they are regarded as a lot, the two specimens are under the same catalog number, but originally, they had different numbers: the larger specimen was labeled MHNCT 14-81, and the smaller, MHNCT 14-82. We propose that the labeling be changed after this publication and differentiate the specimens by placing letters A and B in the inventory number at the end.

Detailed morphological studies were conducted on the specimens, focusing on their size, shape, and distinctive features. The specimens were also compared with contemporaneous faunas from other regions to ascertain their evolutionary and ecological significance.

Geological Setting

 ⌅

In 1961, workers discovered specimens from a 45-meter-high wall outcrop at the “El Ají” quarry, situated near Campechuela, Granma province, eastern Cuba. This location exposes the early Middle Eocene El Caney Formation (Fm), and the specimens seem to originate from it (refer to Figure 1).

Figure 1.  A: Map of Cuba, B: Satellite map of part of eastern Cuba showing the location of El Aji quarry (red star) - a locality near Campechuela (Granma Province) where the fossil fish specimens discussed in this report originated, C) Geology of the studied area (Map courtesy of Rafael Coutin-Lambert).
Figura 1.  A: Mapa de Cuba, B: Mapa satelital de una parte de Cuba oriental mostrando la ubicación de la cantera El Ají (estrella roja) - una localidad cerca de Campechuela (Provincia de Granma) de donde provienen los peces fósiles discutidos en esta contribución, C) Geología del área estudiada (Mapa cortesía de Rafael Coutin-Lambert).

The El Caney Formation belongs to the upper part of El Cobre Group and crops out on the northwestern and northeastern slopes of the Sierra Maestra (Granma and Santiago de Cuba provinces). It is characterized by pyroclastic and sedimentary rocks, conglomerates, and lava flows (García-Delgado and Torres-Silva, 1997García-Delgado, D., and Torres-Silva, A. (1997). Sistema Paleógeno. In: Furrazola-Bermúdez, G., and Núñez Cambra, K. (eds.), Estudios sobre Geología de Cuba (pp. 115-140). La Habana, Centro Nacional de Información Geológica.; Iturralde-Vinent, 1996Iturralde-Vinent, M. (1996). Cuba: El archipiélago volcánico Paleoceno-Eoceno medio. In: Iturralde-Vinent, M., (Ed.) Cuban Ophiolites and Volcanic Arcs vol. 364. IGCP, Miami, FL, USA, pp. 231-241., 2021Iturralde-Vinent, M. (2021). Geología de Cuba, Compendio 2021. Apk. Ediciones CITMATEL (https://www.libreriavirtualcuba.com/geologia-de-cuba-compendio-2021).; Sokolova, 1966Sokolova, E. A. (1966). Conferencia sobre las formaciones vulcanógeno-sedimentarias que contienen manganeso en la provincia de Oriente. Oficina nacional de Recursos Minerales, La Habana, 15.). It lies concordantly over the Lower Eocene Pilón Formation and below the Middle Eocene Puerto Boniato Formation. The foraminifera assemblage includes the following index taxa: Morozovella aequa, M. aragonensis, Acarinina brodermanni, Discocyclina barkeri, Pseudophragmina (Pseudophragmina) cedarkeyensis, Amphistegina cubensis, Eoconuloides wellsi, Helicolepidina spiralis (Iturralde-Vinent, 2021Iturralde-Vinent, M. (2021). Geología de Cuba, Compendio 2021. Apk. Ediciones CITMATEL (https://www.libreriavirtualcuba.com/geologia-de-cuba-compendio-2021).). The El Caney Fm was deposited in an open marine basin, in the final stage of the Paleogene volcanic arc, mostly during the early Middle Eocene, with abundant contribution of tuffogenic and terrigenous material.

Results

 ⌅

Systematic paleontology

 ⌅

  • Order PERCOPSIFORMES Berg, 1940

  • Suborder PARACANTHOPTERYGII

  • Family PERCOPSIDAE Agassiz, 1850Agassiz, L. 1850 (16 July). New species from Lake Superior described by M. Agassiz. American Journal of Science and Arts, 2 (10), 125-127.

  • Fishia incertae sedis: gen. sp. indet.

Material

 ⌅

MHNCT 12-23-A, a complete articulated fish skeleton with traces of soft tissues and scales on matrix (preserved in halves) - Figures 2- 7.

Locality and age

 ⌅

The specimen was collected from “El Ají” quarry, near Campechuela, Granma, in matrix of the early Middle Eocene El Caney Formation.

Description

 ⌅

Elongated specimen with a large head and well-developed pelvic and dorsal fin. The specimen seems to have been preserved in an oblique or slanted position, and the head is thus preserved perpendicularly (on dorsal view). The skull is widest posteriorly, with a narrow supraoccipital, but rounded cranium. A sagittal suture is slightly visible running midway through the cranium. There is no evident raised crest. There are no apparent, additional sutures. The orbit is not visible, but the upper maxillary and dentary do not seem to extend closely to the front of the eyes. The opercular bones are large and ovoid, scattered posteriorly, and openly. The ceratohyal is elongated and arched (Figures 2- 4). Several possible accessory fin rays and spines can be observed towards the dorsum-neck area. The anterior portion of the skull (nasal frontal) tapers gradually into a thin point towards what could be the maxilla, premaxilla, or palatine. Traces of possible stub-like teeth are hardly detectable on this specimen (X-ray imaging has not been possible). Traces of the basipterygia can be inferred in the ventral nape, behind the opercular or supraopercular bones. The cephalic canal is not evident in this specimen. The hypohyal and anterior ceratohyal elements are not well preserved in this specimen, but there are large flat-bone impressions that could represent this element (Figure 4). The dorsal spine does not originate at the occiput.

Figure 2.  MHNCT 12-23-A from El Ají quarry, near Campechuela (Granma Province), Early-Middle Eocene, El Caney Formation (set in tuffaceous matrix).
Figura 2.  MHNCT 12-23-A de la cantera El Ají, cerca de Campechuela (Provincia de Granma), Eoceno Medio temprano, Formación El Caney (incrustado en matriz tufácea).
Figure 3.  Superposition and line drawing (B) for specimen MHNCT 12-23-A (A) demonstrating general tentative osteology. Drawing by JO.
Figura 3.  Superposición y dibujo lineal (B) del ejemplar MHNCT 12-23-A (A) mostrando una osteología tentativa general. Dibujo por JO.
Figure 4.  Skull osteology (A) and indicated (B), tentative, terminology of specimen MHNCT 12-23-A.
Figura 4.  Osteología del cráneo (A) e indicación (B), tentativa, de la terminología del ejemplar MHNCT 12-23-A.

The specimen contains ~30 vertebrae, of which seven are precaudal, located in the anterior portion of the dorsal nape. The thoracic contains hemal and hemapophyses on the ventral side of the vertebral body, originating dorsally, and zygapophyses also on the dorsal, with traces of intermuscular bones, and what could be remains of rays. The ribs and spines are generally attached to the centrum of the vertebrae, except towards the caudal fin. Some of the vertebral processes seem fused. The neural spines are usually attached to the vertebral centrum and arched posteriorly. The vertebral intercentrumise is well-defined, with accentuated pleurocentrae. Prezygapophises are more accentuated than postzygapophyses in the cephalad vertebrae, whereas the opposite is true in the caudal, tapering towards the hypurals (Figures 3, 5, and 6).

The specimen has well-preserved and developed dorsal and anal fins, of which the first is the largest. The anal fin is sub-squared, and its posterior margin is near straight. The dorsal fin is curved and tapers at the tip. The dorsal fin lies midway between the pelvic (anterior-most) and anal fins (posterior-most). The pelvic fin is poorly preserved, but it is represented by five thick spines. Small traces of accessory thin rays or fragments of a pectoral fin lie immediately posterior to it.

Figure 5.  Example of scale and soft tissue preservation on specimen MHNCT 12-23-A.
Figura 5.  Ejemplo de conservación de escamas y tejido blando en el ejemplar MHNCT 12-23-A.
Figure 6.  Fossilized counterpart of specimen MHNCT 12-23-A. Note the vertebral body and abdominal spine arrangement.
Figura 6.  Contraparte fosilizada del ejemplar MHNCT 12-23-A. Observe el cuerpo vertebral y la disposición de las espinas abdominales.

Articulated to the pelvic fin is a series of ribs, intermuscular bones, and hemal spines. These fins have both spinous and soft rays. The anal fin has ~ eight hard spines and ~ eight soft bifurcating rays towards the tips. The dorsal fin has nine hard, spines in the same mode as the dorsal fin (Figure 7). These spines tend to bifurcate towards the distal ends, whereas they are thicker toward their origins. There seem to be a few floating ribs at the distal spinous ray fins in the anal and pelvic fins. There are no vestiges of an adipose fin on this specimen. However, evidence of a possible tissue bulge (‘?’ in Figure 3) between the dorsal fin and caudal peduncle. This area does not contain superficial evidence of spines or rays, and thus cannot be identified as a small fin.

Figure 7.  Caudal fin osteology (A, B) with indicated (tentative) terminology of specimen MHNCT 12-23-A.
Figura 7.  Osteología de la aleta caudal (A, B) con terminología indicada (tentativa) del ejemplar MHNCT 12-23-A.

The tail is incomplete, containing hard, grooved spines and bifurcation fin rays towards the tips of the fin. The caudal fin is truncated and does not seem forked or notched. There are at least six, well-defined caudal vertebrae with preural centrum (Figure 7). The most posterior attachment of neural-hemal spines occurs at the third caudal vertebrae from the hypural. The parahypural are slanted, covered in soft fine rays. The hypural seems more solid and fussed. From both structures, at least 15-16 hard spines arise. Six accessory or rudimentary fin rays lie over them on the vertices of the tail.

Thanks to the exceptional preservation of this specimen, a soft tissue silhouette is evident. It shows a round, bulging head with an elongated nape and caudal peduncle. Remnants of scales and fragments of skin are also observable towards the head and trunk. The scales have a crosshatching cycloid pattern of laterally compressed ganoid (rhomboid) scales (Figure 5). The openings or lateral line canals are thin. Since the specimen is slightly rotated, what seem to be parts of the second pelvic fin can be observed behind the head, and in front of the dorsal fin. The full ossification suggests the specimen was likely an adult (although perichondral elements have not been preserved in this specimen).

Comparisons

 ⌅

Percopsidae is a family of five genera of small, elongated fish that are endemic to North America, where they are known from both marine and freshwater environments. Only one genus remains extant, Percopsis, whereas four are extinct: Amphiplaga, Erismatopterus, Lateopisciculus, and Libotonius, known from Paleocene-Eocene (~66-41 Ma) freshwater-lake deposits (Wilson, 1979Wilson, M.V. (1996). The Eocene fishes of Republic, Washington. Washington Geology, 24 (2), 30-31.; Grande, 1984Grande, L. (1984). Paleontology of the Green River Formation, with a review of the fish fauna. Geological Survey of Wyoming Bulletin, 63, 1-133. ; Murray and Wilson, 1996Murray, A. M., and Wilson, M. V. (1996). A new Palaeocene genus and species of percopsiform (Teleostei: Paracanthopterygii) from the Paskapoo Formation, Smoky Tower, Alberta. Canadian Journal of Earth Sciences, 33 (3), 429-438. ). Their earliest fossils are known from the Paleocene, but their origins could extend to the Cretaceous (Cavender, 1986Cavender, T. M. (1986). Review of the fossil history of North American freshwater fishes. In: Hocutt, C. H., and Wiley, E. O. (eds), The Zoogeography of North American Fresh Water Fishes (pp. 699-724). John Wiley and Sons, New York. ). Percopsids have a diet of insects and small crustaceans.

Specimen MHNCT 12-23-A display the following diagnostic discrete characters of the percopsid family: The premaxilla contains a single row of teeth; the opercular bones are serrated on the posterior margin; the postemporal has a narrow and elongate process, with a lunate-shaped supraoccipital (Agassiz, 1849Agassiz, L. (1849). Two new fishes from Lake Superior. In Proceedings of the Boston Society of Natural History, 3, 1848-1851., 1850Agassiz, L. 1850 (16 July). New species from Lake Superior described by M. Agassiz. American Journal of Science and Arts, 2 (10), 125-127. ; Murray, 1996Murray, A. M. (1996). A new Paleocene genus and species of percopsid, † Massamorichthys wilsoni (Paracanthopterygii) from Joffre Bridge, Alberta, Canada. Journal of Vertebrate Paleontology, 16 (4), 642-652. ; Polly, 2004Polly, W. (2004). Family Percopsidae Agassiz 1850 - trout perches and sand rollers. California Academy of Science Annotated Checklists of Fishes, 23, 1-5. ).

Our specimen differs from Amphiplaga brachyptera and Erismatopterus levatus in several important diagnostic features. The head of A. brachyptera and E. levatus is not as elongated, and the nape is pronounced. The frontal-nasal and occipital areas of the cranium are also shorter and thicker in Amphiplaga and E. levatus. The main difference lies in the morphology of the dorsal and pelvic fins. In Amphiplaga and Erismatopterus, these are near the same size (the dorsal slightly larger). The pelvis is much larger and flipper-like than in both genera. Our specimen lacks a pectoral fin (which could be due to preservation and not morphology), present in Amphiplaga and Erismatopterus. The vertebrae seem much smaller in Amphiplaga and Erismatopterus than in MHNCT 12-23-A, and the thoracic ribs and spines are of unequal size (same size in Amphiplaga and Erismatopterus).

They are similar, however, in having at least eight hard spines, with fine bifurcating rays towards the tips. They both have similar accessory fin rays on the vertices of the tail. The scale pattern crosshatching is also congruent.

  • In caudal fin osteology, specimens differ considerably from several extant and fossil percopsids mentioned above, particularly in the arrangement and morphology of the parhypural and hypurals. These elements in the extant polymixiiform Plumixia nobilis, the Cretaceous Sphenocephalus brachypterygius, in addition to the percopsids and lobotoniids Percopsis omiscomaycus, Amphiplaga brachyptera and Erismatopterus levatus (after Borden et al., 2013Borden, W. C., Grande, T., and Smith, W. L. (2013). Comparative osteology and myology of the caudal fin in the Paracanthopterygii (Teleostei: Acanthomorpha). Mesozoic fishes, 419-455.; Rosen and Patterson, 1969Rosen, D. E., and Patterson, C. (1969). The structure and relationships of the paracanthopterygian fishes. In: Greenfield, D. W. (ed.) Systematic Ichthyology: A Collection of Readings (pp. 32-52). MMS Information Corporation, New York. ) are elongated and palate-like; much broader in direction of the tail-tip. In MHNCT 12-23-A, these osseous elements are much more reduced and grouped. Although they are tapered caudally and wider caudally (much smaller palette-like form) their articulation to the first pleural and ural centrum is not superimposed, but straight and direct. In this sense, it resembles the percopsiform Massamorichthys wilsoni and basal Mcconicthys sp. (Grande, 1988Grande, L. (1988). A well-preserved paracanthopterygian fish (Teleostei) from freshwater lower Paleocene deposits of Montana. Journal of Vertebrate Paleontology, 8 (2), 117-130.; Murray, 1996Murray, A. M. (1996). A new Paleocene genus and species of percopsid, † Massamorichthys wilsoni (Paracanthopterygii) from Joffre Bridge, Alberta, Canada. Journal of Vertebrate Paleontology, 16 (4), 642-652. ) in addition to the esocid Esox kronneri illustrated in Grande (1999: 280)Grande, L. (1999). The first Esox (Esocidae: Teleostei) from the Eocene Green River Formation, and a brief review of esocid fishes. Journal of Vertebrate Paleontology, 19 (2), 271-292.. These are sister taxa to extant trout perches, mostly recovered from shallow lake deposits (freshwater) (op. cit.).

  • Tentatively identified as a “robalo” or snook (Centropomus undecimalis) originally by the fossil’s discoverers, this specimen does not seem to represent a specimen of the Centropomidae.

Remarks

 ⌅

This specimen may represent a percopsid new genus and species, that existed in the paleo-Caribbean during the Eocene. However, more detailed comparisons and analyses are required to properly diagnose and name this specimen.

  • Order PERCIFORMES Bleeker, 1859

  • Suborder LABROIDEA, Bleeker, 1859

  • Family LUTJANIDAE or CICHLIDAE

  • Fishia incertae sedis: gen. sp. indet.

Material

 ⌅

MHNCT 12-23-B, near complete articulated fish skeleton with soft tissue silhouette in matrix. Figures 8- 9.

Locality and age

 ⌅

The specimen was collected from the "El Ají" quarry, near Campechuela (Granma Province), in sediments of the early Middle Eocene El Caney Formation.

Description

 ⌅

Well-preserved, near complete, and fully articulated fossil fish skeleton with soft tissue silhouette. The specimen is generally small and short, about ~ 12 cm in length. The head is large with a large, ovoid open orbit, preserved in lateral view (Figures 8- 9). The cranium is short but thick in the frontals and nasals. Two probable sphenotic bones are visible posterior to the orbit. The orbit is smaller than the snout length. The dorsal spine does not originate above the occiput. The premaxilla is regular. The remains of the maxilla are evident below. This element is nearly straight pallet-like, tapering caudally. Small, stubby teeth are preserved in the dentary and distal premaxilla. The dentary is wedge-shaped, and thicker caudally. The dentary articulation lies under or at the anterior margin of the orbit. The premaxilla seems to contain a sinus or fenestra (opening). The supraoccipital is wide and rounded, immediately posterior to and not fully fused to the frontal bone. The opercular bones are large, ovoid, flattened, and moderately wide and striated, covering most of the lateral aspect of the head. A large, flat bone lies (interneural?) just behind the supraoccipital. The remains of a pectoral arch seem to be preserved ventrally at the gills.

Figure 8.  Articulated skeleton and soft tissue silhouette of specimen MHNCT 12-23-B from El Ají quarry, near Campechuela (Granma Province) set in fine grain tuffaceous slab of the early Middle Eocene El Caney Formation.
Figura 8.  Esqueleto articulado y silueta de tejido blando del ejemplar MHNCT 12-23-B de la cantera El Ají, cerca de Campechuela (Provincia de Granma) incrustado en una losa tufácea de grano fino de la Formación El Caney del Eoceno Medio temprano.

  • The body extends nearly three times the size of the head and it includes three well-preserved spinous fins. The dorsal fin is the largest, extending from the nape, nearly behind the head, to a shirt caudal peduncle - thus covering most of the dorsal length. There is a small soft tissue gap between the head and the remains of a pterygophore that extends nearly most of the dorsal fin. The remains of scales are evident in that region. The dorsal fin is supported by 13-14 spinous rays attached to dorsal ribs (and intermuscular bones?). The pelvic or pectoral fin is poorly preserved, but it seems to have been small, with ~ 5 spinous rays, supported by thoracic, and ventral ribs (Figures 8- 9). The anal fin is larger than the pelvic or pectoral fin, and more squared in shape. This fin has ~ 10-11 hard rays. Remains of soft rays can be seen distally, within the ghost of soft tissues.

  • The tail is small, nearly the size of the head, and slightly forked or emarginated. Remains of scales can also be noted in that region. The backbone terminates abruptly, proximally, the caudal fin origin. These are ctenoid (elasmoid?) or cycloid. The urohyal and hypurials are not well preserved, thus inhibiting a better assessment of the caudal fin osteology. There are approximately 16-17 caudal fin rays, with the soft rays appearing progressively thinner towards the tip. There seems to be a gap or missing section between the first caudal vertebra and the caudal fin osseous elements. The last hemal spine attached to the centrum is at the second caudal vertebra. The neural and hemal spines are of similar size and thickness. The larges lie in the thoracic region. Accessory fin rays are present on the vertices of the tail.