Bollettino SPI Vol. 61 (1)

Published in June 2022

Index

  • Harper E.M. (2022) – INVITED PAPER – OPEN ACCESS!

Hunting evidence for the Mesozoic Marine Revolution: progress and challenges
pp. 1-18
doi:10.4435/BSPI.2022.03

The 1970’s saw a stream of papers that crystallised the notion of a “Mesozoic Marine Revolution” during which the pace and intensity of biotic interactions (predation, competition and substrate disturbance by grazing and bioturbation) increased and had a marked eff ect on benthic marine communities. The tantalizing ideas and hypotheses which have stemmed from this time have had a lasting effect on the course of palaeoecological studies. Of all the interactions, predation has been most amenable to study but even then, only a subset has been interrogated; the fi eld has been dominated by the study of drilling predation in largely molluscan prey. However, there has been considerable progress in broadening our data gathering activities in terms of prey taxa and styles of predatory evidence, ecosystems and geographic regions investigated. This review concentrates on fi ndings since 2000, identifying areas where great progress has been made and describing locations, such as the northern high latitudes and Tropics and the deep sea, intertidal zone and freshwater ecosystems, where information is lacking but probably tractable. Nevertheless, it is imperative that even for well-studied systems we collect more fossil data from any setting or geographic region in order to take account of the variability seen in the patchwork mosaic of modern marine habits, even in shallow water.

  • Bianucci G. & Collareta A. (2022) – INVITED PAPER – OPEN ACCESS!

An overview of the fossil record of cetaceans from the East Pisco Basin (Peru)
pp. 19-60
doi:10.4435/BSPI.2022.04

The East Pisco Basin is one of the forearc basins that formed during the Cenozoic along the coast of Peru due to the subduction of the Farrallon-Nazca plate beneath the South American plate. The sedimentary fill of this basin is extensively exposed along the coastal Ica Desert, and includes a succession of Eocene to Pliocene marine sediments that account for a ~50-myr-long history of semi- continuous deposition. These rocks are characterized by an outstanding fossil content that remarkably contributed to our understanding of the evolutionary history of the main groups of Cenozoic marine vertebrates. In the Ica desert, the most common and signifi cant vertebrate remains belong to cetaceans. Knowledge on the fossil cetaceans of the East Pisco Basin has grown dramatically in the last fifteen years thanks to several international research projects involving, among many others, the authors of the present article. These research efforts have led to the discovery of several hundred fossil skeletons, the most significant of which have been collected, prepared and partly published. Furthermore, interdisciplinary studies were also conducted in order to provide a high resolution chronostratigraphic framework for this fossil record. Remarkable cetacean specimens come from the Yumaque member of the Paracas Formation (middle to late Eocene), the Otuma Formation (late Eocene), the Lower Miocene (~19-18 Ma) portion of the Chilcatay Formation, and allomembers P0 (14.8-12.4 Ma), P1 (9.5-8.5 Ma) and P2 (8.4-6.7 Ma) of the Middle Miocene to Pliocene Pisco Formation. The Lutetian (42.6 Ma) Yumaque strata are home to the quadrupedal protocetid archaeocete Peregocetus pacificus, which documents the first arrival of cetaceans in the Pacific Ocean. Geologically younger (36.4 Ma) Yumaque deposits have yielded the holotype skeleton of Mystacodon selenesis, the oldest mysticete ever found. This ancestor of the modern baleen whales had a skull provided with a complete dentition and retained hindlimbs, albeit reduced in size. In the Otuma Formation, a nine-m-long basilosaurid (Cynthiacetus peruvianus) has been discovered. The Chilcatay Formation records the first great radiation of the odontocetes, represented by Inticetidae (Inticetus vertizi), basal Platanidelphidi (Ensidelphis riveroi), Squalodelphinidae (Furcacetus flexirostrum, Huaridelphis raimondii, Macrosqualodelphis ukupachai and Notocetus vanbenedeni), Platanistidae (aff . Araeodelphis), Physeteroidea (Rhaphicetus valenciae and cf. Diaphorocetus), Chilcacetus cavirhinus, indeterminate Eurinodelphinidae, and Kentriodontidae (Kentriodon). Overall, this roughly coeval assemblage displays a considerable disparity in terms of skull shape and body size that is possibly related to the development of diff erent trophic strategies, ranging e.g., from suction to raptorial feeding. In the Pisco Formation, starting from P0, the baleen-bearing whales (Chaeomysticeti) represent the most frequent cetacean fossils (only a few mysticetes are known from the Chilcatay strata). Two chaeomysticete lineages are found in the Pisco Formation: Cetotheriidae (from Tiucetus rosae in P0 to Piscobalaena nana in P2) and Balaenopteroidea (from Pelocetus in P0 to several undescribed species of Balaenopteridae in P2, testifying to a progressive trend toward gigantism). Odontocetes are rare in P0, the “kentriodontid” Incacetus broggii being the only species described from these strata, but they become more abundant and diverse in P1 and P2. In P1, the commonest toothed whale is Messapicetus gregarius, a member of Ziphiidae featuring an extremely elongated rostrum and a complete set of functional teeth. Another ziphiid from P1 is Chimuziphius coloradensis, known only from the fragmentary holotype cranium. The P1 strata also record the appearance of the crown Delphinida, with the superfamily Inioidea being represented by two small pontoporiids (Brachydelphis mazeasi and Samaydelphis chacaltanae) and one iniid (Brujadelphis ankylorostris). Moreover, P1 is also home to the stem physeteroid Livyitan melvillei; featuring a three-m-long skull and teeth reaching 36 cm in length, L. melvillei was one of the largest raptorial predators and, possibly, the biggest tetrapod bite ever found. Acrophyseter is another macroraptorial sperm whale, distinctly smaller than L. melvillei, known from both P1 and P2. Even smaller in size are the kogiids Platyscaphokogia landinii and Scaphokogia cochlearis, both of which are known from the upper strata of P2. The same allomember is also home to the ziphiids Chavinziphius maxillocristatus and Nazcacetus urbinai, the “kentriodontids” Atocetus iquensis and Belenodelphis peruanus, and undescribed members of Phocoenidae.

  • Angelone C., Čermak S., Moncunill-Solé B. & Rook L. (2022)

The body mass of Paludotona (Lagomorpha, Mammalia): first approach to the ecology of the last stem lagomorph (Tusco-Sardinia palaeobioprovince, Late Miocene)
pp. 61-70
doi:10.4435/BSPI.2022.01

Paludotona, an insular lagomorph genus endemic of the Tusco-Sardinia palaeobioprovince (~8.3-6.7 Ma), is the last representative of the heterogeneous basal group of early lagomorphs. It post-dates the last appearance datum of stem lagomorphs to 6.7 Ma, i.e., by 2.5 my with respect to the previous datum. This makes Paludotona, during the Late Miocene, a living fossil thriving in an insular refugium. We have a record of only the last 15% or less of the temporal distribution range of Paludotona: in fact Paludotona developed in isolation sensu lato as a ghost lineage for at least 14 my. Paludotona matched the pattern followed by small mammals in insular environments, acquiring a gigantic size with respect to continental ancestors. Its body mass (BM) is here estimated in ~1100 g, i.e., three to five times the BM of the taxa here taken as reference for European MP28-MN1 stem lagomorphs, the group from which Paludotona likely stemmed. The reasons for such an enormous BM increase are multiple and interconnected: synecological factors s.l., lower extrinsic mortality, changes in size and degree/pattern of fragmentation of the area of the insular palaeobioprovince, and successive climate changes (which caused a rapid evolutionary pulse followed by a relative stasis following the pattern of Mein’s biphasic model). At any rate, through BM estimation and morphological observation we discuss some biological traits of Paludotona: there is evidence of increased lifespan (though, at present, not quantitatively determined), and we suspect a change in posture and locomotion caused by the noticeable BM increase.

  • Corriga M.G., Floris M. & Corradini C. (2022)

The Silurian/Lower Devonian sequence at Perda S’altari (SW Sardinia, Italy)
pp. 71-86
doi:10.4435/BSPI.2022.02

In the Perda S’altari area, north of Fluminimaggiore, black shales of the Silurian Genna Muxerru Formation and limestones of the Devonian Mason Porcus Formation are exposed. The area is strongly tectonized, and poorly preserved fossils occur only in a few outcrops. Graptolites of Telychian and Rhuddanian age have been collected from the shales, whereas conodonts indicate the Lochkovian Icr. postwoschmidti and Ad. transitans zones. The problematic Eurytholia bohemica species is here documented from Devonian rocks for the first time outside the Czech Republic. A gradual transition between the Genna Muxerru Fm. and the Mason Porcus Fm. suggests an update to the lithostratigraphical scheme of the Silurian and Lower Devonian of SW Sardinia.