Thursday, August 6, 2020

New fossil mollusk form the Eocene of Cuba

Mollusks are one of the most diverse organisms of the animal kingdom. They inhabit most types of habitats and are extremely diverse in their forms. Octopi and the extinct ammonoids are also mollusks. Within the Mollusca, the so-called phylum of the mollusks, there is the Bivalvia or bivalves. The bivalves are also diverse in their shape, form, and habitat. The group includes clams, cockles, mussels, oysters, and scallops. They have existed for at least 520 million years - since the early Cambrian and appear in most part of the Earth's fossil record. 


During the Eocene - or about 33 to 56 million years ago, the Antillean islands did not exist in the configuration that is known today. In fact, most paleogeographic reconstructions suggest the whole area was a deep marine environment, flanked by two main bank systems (Florida and Yucatan), with small volcanic islands scattered through. The rocks and substructures that would make the Greater Antillean arch later, during the late Eocene - early Oligocene (~33 million years ago), did not yet exist. However, there is no doubt these waters held mollusk faunas - a story that can be told by their fossils. 

Our recent paper in the Journal of South American Earth Sciences (here) describes two unreported species from the Cuban Eocene: the genera Schedocardia and Acanthocardia. The fossilized remains of these mollusks, still encased in rock-matrix, were collected at the Madruga Formation a couple of years ago by Yasmani Ceballos, one of the authors of our paper. This Formation includes microscopic organisms, corals, brachiopods, and sea urchins from the Late Paleogene and Early Eocene - and thus provides a window into the marine life of Cuba's early seas. Equally important, these two fossils represent forms that had not been reported from the Cuban fossil record! 

A free copy of our paper can be downloaded for free on the ScienceDirect page, but only until September 18, 2020. Don't miss the opportunity to acquire the paper now. 

Recommended citation

Orihuela, J., Y. Ceballos Izquierdo, R. W. Portell (2020). First report of the Eocene bivalve Schedocardia (Mollusca, Cardiidae) from Cuba. Journal of South American Earth Sciences, Vol. 103. https://doi.org/10.1016/j.jsames.2020.102771

Saturday, June 13, 2020

On Antillean vertebrate bat extinctions: PCMDOMINICANA YouTube talks

Our colleagues from the Dominican Republic treated us, this past week, to a series of online lectures on Caribbean bats by the world’s forefront researchers. Each day a different specialist spoke of their research and what is known and unknown about bats. These included talks by Nancy Simmons, Paul Velazco, Liliana Davalos, and Angelo Soto Centeno. 


I want to share Centeno’s talk here and take the opportunity to thank him for mentioning our own ongoing research on Greater Antillean vertebrate extinctions and biodiversity (time stamp 36:20). Many thanks, Angelo! 

I also thank our friends at the PCM from Republica Dominican and their great initiative with the YouTube channel.

Pteronotus quadridens from Los Haitises, Dominican Republic. (C Joha Orihuela, 2004). 

Collagen sequence reveals evolutionary history of extinct 'island-shrews' - Nesophontes

With great satisfaction, I announce the publication of our paper on the extinct Greater Antillean endemic: Nesophontes. As you may have read from posts in this blog, the genus Nesophontes is a group of shrew-like mammals for which several species have been identified on the islands of Cuba, Cayman, Hispaniola, and Puerto Rico, but not The Bahamas or Jamaica. Each island had its own exclusive forms. These unique varieties to each island are called endemics. 

Original specimen from which Nesophontes was described: N. edithae (AMNH 14174). 

The genus Nesophontes is grouped within the mammal order Eulipotyphla. This is a group of basal placental mammals that are considered ancestrally associated to the Solenodon of Cuba and Hispaniola. Also, to other North American extinct shrew-like micromammals, but surprisingly not to the African tenrecs despite their physical similarity.  Nesophontes was small, likely venomous, nocturnal, and could tunnel underground. At least eight species are currently recognized: three in Cuba (N. major, N. micrus and N. longirostris); three in Hispaniola (N. paramicrus, N. hypomicrus, and N. zamicrus); one in Puerto Rico (N. edithae) and one in Cayman (N. hemicingulus). However, the identification, naming, and evolutionary history of this diverse group has been somewhat controversial. 

Solenodon paradoxus from Hispaniola. Plate from Allen's (1910) monograph on the species. 


We designed our study to help unravel especially the issue of evolution and species limits. Our paper, formally accepted in the journal Molecular Biology and Evolution this past march, provides the following abstract: 

“Ancient biomolecule analyses are proving increasingly useful in the study of evolutionary patterns, including extinct organisms. Proteomic sequencing techniques complement genomic approaches, having the potential to examine lineages further back in time than achievable using ancient DNA, given the less stringent preservation requirements. In this study, we demonstrate the ability to use collagen sequence analyses via proteomics to provide species delimitation as a foundation for informing evolutionary patterns. We uncover biogeographic information of an enigmatic and recently extinct lineage of Nesophontes across their range on the Caribbean islands. First, evolutionary relationships reconstructed from collagen sequences reaffirm the affinity of Nesophontes and Solenodon as sister taxa within Solenodonota. This relationship helps lay the foundation for testing geographical isolation hypotheses across islands within the Greater Antilles, including movement from Cuba towards Hispaniola. Second, our results are consistent with Cuba having just two species of Nesophontes (N. micrus and N. major) that exhibit intrapopulation morphological variation. Finally, analysis of the recently described species from the Cayman Islands (N. hemicingulus) indicates that it is a closer relative to the Cuban species, N. major rather than N. micrus as previously speculated. Our proteomic sequencing improves our understanding of the origin, evolution, and distribution of this extinct mammal lineage, particularly with respect to approximate timing of speciation. Such knowledge is vital for this biodiversity hotspot, where the magnitude of recent extinctions may obscure true estimates of species richness in the past.”

I take this opportunity to extend my gratitude and thanks to the whole team, for pushing through with persistence for nearly a decade. And to all the friends and colleagues that helped along the way. 

Stay tuned for more details on our findings and these peculiar mammals ahead. 


Recommended Citation

Buckley, Mike; Virginia L. Harvey; Joha Orihuela; Alexis M. Mychajliw; J. Keating; J. N. Almonte Milan; C. Lawless; A. T. Chamberlain; V. M. Egerton; and Phillip L. Manning (2020). Collagen sequence analysis reveals evolutionary history of extinct West Indies Nesophontes ('island-shrews'). Molecular Biology and Evolution: https://doi.org/10.1093/molbev/msaa137



Wednesday, January 29, 2020

New papers and preprints on antillean vertebrate extinctions now available!

Hi there internet surfers and blog-verse travelers, what a great way to start the new year. There are several new research papers and findings now available on Cuban - generally Antillean  - Late Quaternary land vertebrate extinctions. A lot of exiting and revealing new data, on which I will expand in future blog posts; hopefully, soon.

In the mean time, here I share some links for those interested in our new data and preprints.

Our new paper on Cuba bats is now available on my ResearchGate page here, or on the Novitates Caribaea journal page, here. To see a post on this research, visit here.

Three of our preprints posted on BioRxiv are available there, and they are citable as:

J. Orihuela, Lázaro W. Viñola, Osvaldo Jiménez Vázquez, Alexis Mychajliw, Odlanyer Hernández de Lara, Logel Lorenzo, J. Angel Soto-Centeno "Assessing the role of humans in Greater Antillean land vertebrate extinctions: new insights from Cuba" bioRxiv 2020.01.27.922237;doi: https://doi.org/10.1101/2020.01.27.922237

J. Orihuela, Leonel Pérez Orozco, Jorge L. Álvarez Licourt, Ricardo A. Viera Muñoz, Candido Santana Barani "Late Holocene land vertebrate fauna from Cueva de los Nesofontes, Western Cuba: stratigraphy, last appearance dates, diversity and paleoecology"
bioRxiv 2020.01.17.909663; doi: https://doi.org/10.1101/2020.01.17.909663

J. Orihuela, Yasmani Ceballos Izquierdo, Roger W. Portell "First report of the Eocene bivalve Schedocardia (Mollusca, Cardiidae) from Cuba" bioRxiv 2020.02.03.932756; doi: https://doi.org/10.1101/2020.02.03.932756

Extinct Cuban ground sloth Megalocnus rodens. Specimen mounted with remains discovered by Carlos de la Torre
This skeleton is part of the collection at the Cuban National Museum.

Thursday, September 5, 2019

Describing the impossible: a sauropod fossil from Cuba

A joint effort of Cuban-Argentinian paleontologists have recently published a detailed description of a dinosaur fossil found in the rocks of Cuba. With it, the researchers concluded that the fragmentary remain could have belonged to a rare dinosaur group that inhabited the surrounding landmasses of the proto-Caribbean Sea, preserving it in rocks that are now part of the Cuban terrain.

The interesting fossil was discovered at the start of the 20th century, in Jurassic-age rocks of the Jagua Formation, which crop out near Viñales, western Cuba. The fossil, however, did not gain certain attention until it was described and figured in a small note published by the Cuban geologist Alfredo de la Torre y Callejas, in 1949. In it, de la Torre credits the discovery to America Ana Cuervo, a professor of Geology and Paleontology at the University of Havana, and who had published several articles on Cuban fossil reptiles. Apparently, professor Cuervo donated the specimen to the University’s museum, where it was later available to de la Torre.


Metacarpal position for the somphospondylan sauropod from Cuba.
With insert of original specimen found by Prof. America A. Cuervo.
Courtesy of Yasmani Ceballos.
Unfortunately, the fossil has been lost since, and its whereabouts are still a mystery. All that remains of the enigmatic fossil are de la Torre’s vague descriptions and the small photograph published in 1949 (see figure below). Classifying it, based on such scanty data, has no doubt been challenging for the research team, but also very rewarding for Cuban paleontology. Comprising a  rare and noteworthy record indeed.

The research team, composed of Yasmani Ceballos Izquierdo – an upcoming Cuban paleontologist – and Dr. Manuel Iturralde-Vinent – the Cuban geologist-paleontologist extraordinaire, were led by the Argentinian dinosaur specialist Dr. Sebastián Apesteguía. Together, they recently published the interesting findings of their study in the prestigious journal Historical Biology.

Based on detailed comparisons, they have been able to identify the lost fossil bone as pertaining to the hand bone – a metacarpal – representing an old lineage of the Somphospondylii or a basal titanosaurid. These dinosaurs belonged to a group of giant herbivore sauropods that inhabited the coastal lands of Laurasia and Gondwanaland.

Alliance between Cuban and Argentinian paleontologists has spanned over a hundred years, starting with the Argentinian paleontologist Florentino Ameghino, who collaborated with Cuban researchers through the late 19th century. During the 1990s, Dr. Manuel Iturralde worked with Dr. Zulma Gasparini in the identification of rare reptilian fossils found in Jurassic-age rocks from Cuba. The most recent collaboration with Dr. Sebastián Apesteguía, like in the past, has no doubt bore fruitful results.


Metacarpal from somphospondylan sauropod from Cuba.
Original specimen found by Prof. America A. Cuervo.
Courtesy of Yasmani Ceballos.
 
Not only is this the first and only dinosaur yet reported from Cuba, but the fossil is also of biogeographical importance. It brings evidence of the extinct animals that inhabited the area that was to become the Caribbean Sea and some of its islands, like Cuba, several millions of years before the end-Cretaceous mass extinction that wiped out the dinosaurs.

Idealized scene of the western Tethys - early Caribbean seaway, and fauna
known from fossil remains found in Cuba.
Artwork by Roilan. Courtesy of Yasmani Ceballos.

After the supercontinent Pangea broke up, around 200-180 million years ago, it divided into several landmasses. Some to the northern hemisphere, others to the southern hemisphere. Laurasia is the landmass that existed when the North American continent was interconnected to its Eurasian counterpart, several hundred million years ago. The surrounding landmasses had a narrow seaway in which this fossil was probably washed into. The rocks of the bottom of that seaway have long since moved and incorporated to form parts of the main island of Cuba. This fossil, among other biological remains known from similar rocks formations, support the presence of emerged land nearby the proto-Caribbean seaway – known as the western Tethys.


The Earth during the Jurassic period (~200 -145 million years ago). Red circle shows area of proto Caribbean
Artwork and geologic interpretation by Christopher Scotese.


Acknowledgments


I extend my thanks to and appreciation for Yasmani Ceballos, who shared revealing information to prepare this post.

Recommended citation:


Apesteguía, S., Ceballos Izquierdo, Y., and Iturralde-Vinent, M. (2019). New taxonomic assignment for a dinosaur sauropod bone from Cuba. Historical Biology, https://doi.org/10.1080/08912963.2019.1661406