Bollettino SPI Vol. 63 (1)
Published in June 2024
Index
- Cau A. (2024) – OPEN ACCESS!
A Unified Framework for Predatory Dinosaur Macroevolution
pp. 1-19
doi: 10.4435/BSPI.2024.08
Known since the 19th Century, the compsognathids are among the smallest predatory dinosaurs, and include the first feathered non-avian species found. Traditionally, compsognathids have been considered small and unspecialized coelurosaurs, closer to birds than large-bodied forms like allosauroids and megalosaurids. Yet, all known compsognathids are based on skeletally-immature specimens, and this challenges the accuracy of their traditional phyletic placement. Despite the role of heterochrony in dinosaur evolution is widely recognized, the impact of ontogenetic-biased miscodings in shaping theropod phylogenetics is mostly underestimated. Herein, I show that the standard framework of theropod macroevolution is biased by a series of coding artifacts which violate semaphoront equality prescribed by phylogenetic systematics. I introduce “Ontogenetic State Partitioning” (OSP), a novel coding protocol which integrates ontogenetic and morphological variation under a total evidence approach, and apply it to a densely sampled data set focusing on Mesozoic theropods. The phylogenetic analysis dismissed “Compsognathidae” from being a natural group: its members are identified as juvenile morphs nested among several non-maniraptoriform tetanuran lineages. Conservatism in the immature body plan and greater disparity among large-sized adults differentiate the predatory communities dominated by non-coelurosaurian species (e.g., the so called “triumvirates”) from the maniraptoriform-tyrannosaurid faunas (herein named “tyrannies”). This clade-specific differentiation among the communities is confirmed by an analysis of the predatory guild structures including all growth stages: triumvirates and tyrannies result as particular cases along a continuum of communities regulated mainly by alternative contributions of the small- and medium-sized classes. The oldest tyrannies (early Late Cretaceous in age) cluster among non-tyranny communities, supporting the hypothesis that tyrannosaurid-dominated faunas acquired their peculiar structure only after the extinction of the non-coelurosaurian components. The macroevolutionary trajectory that led the maniraptoriforms to realize the avian-like biology may have precluded them from occupying hypercarnivorous large-bodied niches: this bauplan constraint would have favored the tyrannosauroids in opportunistically assuming the apex predatory roles in Late Cretaceous Asiamerica but not elsewhere. The large-scale structure of the Cenozoic radiation of birds is coherent with the framework introduced herein.
- Bianucci G., Benites-Palomino A.M., Collareta A., Bosio G., de Muizon C., Merella M., Di Celma C., Malinverno E., Urbina M.
& Lambert O. (2024) – OPEN ACCESS!
A new Late Miocene beaked whale (Cetacea, Odontoceti) from the Pisco Formation, and a revised age for the fossil Ziphiidae of Peru
pp. 21-43
doi: 10.4435/BSPI.2024.10
The previously scarce fossil record of Ziphiidae (beaked whales) has greatly increased recently thanks to the serendipitous discovery of high specimen concentrations along deep seafloors as well as to abundant inland finds from the Upper Miocene of the Pisco Formation (East Pisco Basin, Peru). In the latter unit, ziphiid remains are indeed among the most prevalent of the whole cetacean assemblage, being represented by four distinct genera and species plus at least two as-yet unnamed taxa. Here, we describe a fifth ziphiid genus and species from the Pisco strata, Mamaziphius reyesi n. gen. n. sp., based on a partial cranium from mid-Tortonian (lower Upper Miocene, 9.1-9.0 Ma) strata exposed at the locality of Cerros la Mama y la Hija. Though reminiscent of the extant genus Berardius, the holotype skull lacks two diagnostic characters of Berardiinae, namely, an isolated rounded protuberance formed by the interparietal or frontals on the posterior part of the vertex, and a posterior transverse narrowing of the nasals and frontals at the vertex. Our phylogenetic analysis reveals that Mamaziphius n. gen. is nested within the crown ziphiids, as sister group of the berardiines. In addition, we introduce two new clade names within Ziphiidae, namely, Messapicetiformes (for the so-called “Messapicetus clade”) and Vomeroziphii (for Ziphiinae + Hyperoodontinae and closely related forms). Another fragmentary specimen from the Pisco Formation is also briefly described herein. Furthermore, a comprehensive reappraisal of the geological age of the fossil beaked whales of Peru is provided based on new age calibrations, thus restricting the whole rich Peruvian record of this family (including the earliest-branching ziphiid, Ninoziphius platyrostris, which comes from Pisco-equivalent strata of the Sacaco area) to a Tortonian-Messinian interval younger than 9.10 Ma. No other inland unit worldwide preserves a record of fossil ziphiids as abundant, diverse and chronostratigraphically well-constrained as the Pisco Formation. In view of this, the absence of Vomeroziphii from the fossil content of the Pisco strata remains quite enigmatic.
- Iannucci A. (2024) – OPEN ACCESS!
Sus arvernensis (Suidae, Mammalia) from the early Villafranchian of Villafranca d’Asti (northern Italy): a revision of the largest sample of a key suid species
pp. 45-81
doi: 10.4435/BSPI.2024.03
The area of Villafranca d’Asti (Piedmont, northern Italy) is best known among mammalian paleontologists for having given its name to the Villafranchian, a term that today refers to a widely adopted biochronological unit, although it was initially proposed to denote a continental stage. Amongst the numerous remains of Pliocene large mammals recovered from the sedimentary basin of Villafranca d’Asti, those of suids (Artiodactyla: Suidae) represent the most abundant sample of Sus arvernensis. This species is the first member of the genus that includes the Eurasian wild boar, Sus scrofa, and many extinct and extant species of suids. Sus arvernensis is considered ancestral or close to the ancestors of several suid lineages, as well as being of relevance for biochronological correlations and paleoecological considerations. It is, indeed, one of the few species of large mammals apparently capable of taking advantage of the return to more humid conditions after the Miocene-Pliocene transition. Despite their importance, Villafranca d’Asti suids have been only partly described in previous studies, or merely summarily considered while comparing other samples. Here, combining the examination of this collection with the analysis of other material, I present a detailed study of the suid sample recovered from the Pliocene of Villafranca d’Asti, which provides new insights into this important sample and broadens our knowledge on the biometric and morphological variability of Sus arvernensis. A careful evaluation of curatorial and historical evidence supports the view of a coherent provenance of the fauna of Villafranca d’Asti from a single level of the RDB quarry (~3.2 Ma, Triversa Faunal Unit), which, although generally accepted in most previous studies, remained in-need of a proper justification. Moreover, preliminary taphonomic considerations based on the suid sample suggest that nearly entire carcasses were originally deposited.
- Walter J.D., Marramà G., Pavia M., Carnevale G. & Delfino M. (2024)
A shark turns into an undetermined crocodylian: the case of Acanthias bicarinatus Sismonda, 1849
pp. 83-87
doi: 10.4435/BSPI.2024.02
The holotype and only specimen referred to the Early Miocene shark Acanthias bicarinatus Sismonda, 1849 is housed in the collections of the Museo di Geologia e Paleontologia dell’Università degli Studi di Torino and was collected from the serpentinite sandstone of the middle-late Burdigalian Termofourà Formation of the Torino Hill. The specimen, formerly interpreted as a fragment of a squalid dorsal-fin spine, is reinterpreted herein as an isolated crocodylian tooth. The validity of the species Acanthias bicarinatus is therefore reconsidered and referred to as a nomen dubium. The tooth, replaced while the crocodylian was alive, was deposited in a near-shore marine environment at a time when modern crocodylian lineages were already widespread along the northern sector of the Mediterranean area.
- Bazzicalupo P., Cipriani M., Guido A., Bracchi V.A., Rosso A. & Basso D. (2024)
Calcareous nannoplankton inside coralligenous build-ups: the case of Marzamemi (SE, Sicily)
pp. 89-99
doi: 10.4435/BSPI.2024.09
In the Mediterranean Sea, crustose coralline algae form mesophotic reefs referred to as Coralligenous. They act as a sediment trap and may be considered as a potential source of geological information. Two coralligenous build-ups collected during the project FISR “CRESCIBLUREEF” at 36 and 37 m water depth off the coast of south-eastern Sicily reveal the presence of calcareous nannoplankton/nannofossil specimens within the sediment infilling. This novel finding reveals the occurrence of a mixed modern and reworked nannoplankton assemblage derived from marine-snow sedimentation and land weathering, respectively. The quantitative analysis of the assemblages from both build-ups shows a difference in sedimentation exposure derived from the different local environments where the build-ups were collected, highlighting the potential role of coccolithophores as a sedimentation proxy for coastal settings.