ARIENIGRAPTUS OF BOLIVIA

Graptolites (Graptolita) are a group of colonial animals known primarily from Ordovician deposits. The biological affinities of the graptolites have always been debatable.

Originally regarded as being related to the hydrozoans, graptolites are now considered to be related to the pterobranchs, a rare group of modern marine animals.

The graptolites are classed as hemichordates (phylum Hemichordata), a phylum of marine deuterostome animals and come in a variety of weird and wonderful designs. They were a major component of the zooplankton in our early Paleozoic ecosystems, most likely living as suspension feeders, drifting freely on the surface of ancient seas or attached to floating seaweed by means of a slender thread. Some forms of graptolite lived attached to the sea-floor by a root-like base. The deceased planktonic graptolites would sink down to and settle on the seafloor, eventually becoming entombed in the sediment and are thus well-preserved.

Graptolite fossils are often found in shales and slates and can be mistaken for scratches on the rock. The name graptolite comes from the Greek graptos meaning "written", and lithos meaning "rock." It is a very suitable name as many graptolites look very much like hieroglyphs written on rock and not the impressions of animals.

Graptolites are common fossils and have a worldwide distribution. The preservation, quantity and gradual change over a geologic time scale of graptolites allow the fossils to be used to date strata of rocks throughout the world. They are important index fossils for dating Palaeozoic rocks as they evolved rapidly with time and formed many different species.

We find graptolite fossils flattened along the bedding planes of the rocks in which they occur. My first graptolite finds were from roadcuts up near Cranbrook, British Columbia, Canada. I was on a fossil field trip looking for Cambrian trilobites. It was a thrilling experience and completely unexpected when the first graptolite met my eyes.

They vary in shape, but are most commonly dendritic or branching (such as Dictoyonema), saw-blade like, or "tuning fork" shaped, such as Didymograptus murchisoni. The lovely specimen of Arienigraptus sp. you see here is from the Lower Darriwilian of Bolivia and in the collections of the deeply awesome Gilberto Juárez Huarachi‎. The second photo is from the Encyclopaedia Brittanica - From the Encyclopaedia Brittanica, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6886878

PERSISTISTROMBUS LATUS

A beautiful example of two water-worn specimens of the gastropod Persististrombus latus (Gmelin, 1791) captured after a storm captured by the deeply awesome José Juárez Ruiz from Palma De Mallorca, Spain.

In his original description of Strombus latus, Gmelin describes this new species in his paper from 1791, page 3520: "latus. 35. Str. testae labro prominulo inferne bis emarginato, spirae anfractu primo medio laevi utrinque transversim striato, reliquis nodis obtusis coronatis."

Persististrombus latus is the most iconic representative of the Senegalese fauna, a fossil assemblage of tropical water organisms thought to have colonized the Mediterranean Sea during the last interglacial period.

Persististrombus latus has become an important stratigraphic marker of Marine Isotope Stage (MIS) 5.5, which allows for the correlation of raised coastal deposits, useful in studying sea-level variations and tectonic uplift.

Persististrombus latus is found in shallow marine sediments of Tyrrhenian age (∼124 ka) in several localities of the Italian peninsula. Gmelin's early work on the species is from upper Pleistocene deposits of the marine terraces of the Crotone peninsula of southern Italy. If you fancy a visit to this locality, head to: N38°45'00" - N39°04'60", E17°04'60" - E17°19'60".

Commonly known as the Bubonian Conch, this species of sea snail is a marine gastropod mollusk in the family Strombidae, the true conchs. These fellows are herbivorous, dining on wee bits of algae, seagrass and other detritus found along the seafloor. They grow to around 2.76" - 6.5" (7cm - 16.5cm). We find them in the fossil record and also as modern shells in the Atlantic Ocean along West Africa, Senegal, Gabon, Cape Verde, Ascension Island and Angola. They like it warm, preferring seas of 57.2 °F - 68 °F (14°C - 20°C).

Ronald Nalin, Valentina Alice Bracchi, Daniela Basso, Francesco Massari; Persististrombus latus (Gmelin) in the upper Pleistocene deposits of the marine terraces of the Crotone peninsula (southern Italy). Italian Journal of Geosciences ; 131 (1): 95–101. doi: https://doi.org/10.3301/IJG.2011.25

Gmelin J.F. (1791). Vermes. In: Gmelin J.F. (Ed.) Caroli a Linnaei Systema Naturae per Regna Tria Naturae, Ed. 13. Tome 1(6). G.E. Beer, Lipsiae [Leipzig]. pp. 3021-3910.

BAETIC CORDILLERA

This beautiful ammonite is Neocomites (Teschenites) flucticulus (Thieuloy, 1977) sharing a large boulder with a delicate, straight-shelled, heteromorph ammonite Bochianites. These beauties were found on a fossil field trip to Hauterivian, Early Cretaceous deposits in the Baetic Cordillera in the Spring of 2019. The Baetic Cordillera is one of the main systems of mountain ranges in Spain along the southern and eastern Iberian Peninsula. There are several productive outcrops here that yield lovely Cretaceous ammonites and other marine species.

Neocomites are known from about a dozen offshore marine deep subtidal Cretaceous deposits in France, Hungary, Italy, Romania, Slovakia and Ukraine. We also find Neocomites in the Cretaceous of British Columbia, Canada.

This lovely specimen is the first Neocomites I've seen come out of fossil deposits in Spain. It was found and prepped by the talented Manuel Peña Nieto of Córdoba, Spain.

RHACOLEPSIS AND CARDIAC OUTFLOW

This concretion contains a partially exposed Rhacolepis Buccalis, an extinct genus of ray-finned fossil fish in carbonate concretion from the Lower Cretaceous, Santana Formation, Brazil.

These ancient fish swam our Cretaceous seas 122-109 million years ago. Interestingly, we've been able to recover complete fossilized hearts from this species using X-ray synchrotron microtomography.

Lara Maldanis and her team published a paper on this back in 2016. They were looking at the evolution of cardiac outflow tracts in vertebrates and had a breakthrough moment when an x-ray revealed enough detail to show that Rhacolepis hearts contain a conus arteriosus containing at least five-valve rows making them a transitional morphology between the primitive, multivalve, conal condition and the derived, monovalvar, bulbar state of the outflow tract in modern actinopterygians.

Le premier et unique géoparc mondial UNESCO est situé dans le Cariri du Ceará (géoparc Araripe), dans l'intérieur semi-aride de la région Nordeste, Brésil. Reference: Maldanis et al. (2016) Heart fossilization is possible and informs the evolution of cardiac outflow tract in vertebrates.