Abstract:The First European Symposium on the Evolution of Crocodylomorpha took place during the XVI Annual Meeting of the European Association of Vertebrate Palaeontologists (EAVP) organized by NOVA University of Lisbon (UNL) in Caparica, Portugal. Fourteen lectures and five posters were presented at the symposium in June 26th–July 1st, 2018. This special issue showcases twelve papers based on symposium contributions.
Body size is fundamental to the physiology and ecology of organisms. Crocodyliforms are no exception, and several methods have been developed to estimate their absolute body sizes from bone measurements. However, species-specific sizes, such as sexually mature sizes and the maximum sizes were not taken into account due to the challenging maturity assessment of osteological specimens. Here, we provide a vertebrae-based method to estimate absolute and species-specific body lengths in crocodylians. Lengths of cervical to anterior caudal centra were measured and relations between the body lengths (snout-vent and total lengths) and lengths of either a single centrum or a series of centra were modeled for extant species. Additionally, states of neurocentral suture closure were recorded for the maturity assessment. Comparisons of total lengths and timings of neurocentral suture closure showed that most extant crocodylians reach sexual maturity before closure of precaudal neurocentral sutures. Centrum lengths of the smallest individuals with closed precaudal neurocentral sutures within species were correlated with the species maximum total lengths in extant taxa; therefore, the upper or lower limit of the species maximum sizes can be determined from centrum lengths and states of neurocentral suture closure. The application of the current method to non-crocodylian crocodyliforms requires similar numbers of precaudal vertebrae, body proportions, and timings of neurocentral suture closure as compared to extant crocodylians.
Body size is fundamental to the physiology and ecology of organisms. Crocodyliforms are no exception, and several methods have been developed to estimate their absolute body sizes from bone measurements. However, species-specific sizes, such as sexually mature sizes and the maximum sizes were not taken into account due to the challenging maturity assessment of osteological specimens. Here, we provide a vertebrae-based method to estimate absolute and species-specific body lengths in crocodylians. Lengths of cervical to anterior caudal centra were measured and relations between the body lengths (snout-vent and total lengths) and lengths of either a single centrum or a series of centra were modeled for extant species. Additionally, states of neurocentral suture closure were recorded for the maturity assessment. Comparisons of total lengths and timings of neurocentral suture closure showed that most extant crocodylians reach sexual maturity before closure of precaudal neurocentral sutures. Centrum lengths of the smallest individuals with closed precaudal neurocentral sutures within species were correlated with the species maximum total lengths in extant taxa; therefore, the upper or lower limit of the species maximum sizes can be determined from centrum lengths and states of neurocentral suture closure. The application of the current method to non-crocodylian crocodyliforms requires similar numbers of precaudal vertebrae, body proportions, and timings of neurocentral suture closure as compared to extant crocodylians.
“…Figure 7.Summary of the distribution of thermometabolism across Archosauria. The phylogeny used is a handmade combination of both trees presented in Puértolas-Pascual et al (2020) and Nesbitt (2011). Red indicates an inferred or known endothermic taxon.…”
Section: Discussionmentioning
confidence: 99%
“…and †Goniopholis simus. Their placement follows the consensual phylogeny presented by Puértolas-Pascual et al (2020). As the phylogenetic comparative method necessitates branch lengths, we dated the trees using the minimal age of apparition of each node.…”
The evolution of thermometabolism in pseudosuchians (Late Triassic to the present) remains a partly unsolved issue: extant taxa (crocodilians) are ectothermic, but the clade was inferred ancestrally endothermic. Here we inferred the thermometabolic regime of two neosuchian groups, Goniopholididae (Early Jurassic to Late Cretaceous) and Dyrosauridae (middle Cretaceous to late Eocene), close relatives of extant crocodilians, in order to elucidate the evolutionary pattern across Metasuchia (Early Jurassic to the present), a clade comprising Neosuchia (Early Jurassic to the present) and Notosuchia (Middle Jurassic until the late Miocene). We propose a new integrative approach combining geochemical analyses to infer body temperature from the stable oxygen isotope composition of tooth phosphate and paleohistology and phylogenetic comparative methods to infer resting metabolic rates and red blood cell dimensions. †Dyrosaurus and †Goniopholis share with extant crocodilians similar lifestyles, body forms, bone tissue organization, body temperatures, metabolic rates, and red blood cell dimensions. Consistently, we infer ectothermy for †Dyrosaurus and †Goniopholis with the parsimonious implication of neosuchians and metasuchians being primitively ectothermic.
“…Crocodyliform Symposia at the Congresso Latinoamericano de Paleontologia de Vertebrados in 2008 (Neuquen, Argentina; Pol & Larsson, 2011), 2011 (San Juan, Argentina), 2019 (Uberlandia, Minas Gerais, Brazil) and 2022 (virtual meeting largely hosted by Brazilian researchers) have brought in researchers from around the world to share new discoveries. Symposia in the 2018 Society of Vertebrate Paleontology (chairs: Holliday & Drumheller), the 2018 European Association of Vertebrate Paleontology (Puertolas‐Pascual et al, 2020) and the American Association for Anatomy (chair: Holliday) have contributed as well. A rising tide of works from around the world during the past 20 years speak to the excitement surrounding crocodilian biology and evolution.…”
Section: Figurementioning
confidence: 99%
“…The study of suchian and crocodilian biology and evolution has seen a wellspring of exciting symposia, special issues, and congregations over the past decade feeding into the work featured in this volume. Crocodyliform Symposia at the Congresso Latinoamericano de Paleontologia de Vertebrados in 2008 (Neuquen, Argentina;Pol & Larsson, 2011) (Puertolas-Pascual et al, 2020) and the American Association for Anatomy (chair: Holliday) have contributed as well. A rising tide of works from around the world during the past 20 years speak to the excitement surrounding crocodilian biology and evolution.…”
Crocodilians inspire researchers and the public alike with their explosive hunting methodologies, distinct craniofacial and dental morphology, and resplendent fossil record. This special issue highlights recent advances in the biology and paleontology of this fascinating lineage of vertebrates. The authors in this volume bring crocodylians and their extinct ancestors to life using a variety of approaches including fieldwork, imaging, 3D modeling, developmental biology, physiological monitoring, dissection, and a host of other comparative methods. Our journey begins with early crocodylomorphs from the Triassic, carries us through the radiation of crocodyliforms during the rest of the Mesozoic Era, and finally celebrates the diversification development and biology of extant crocodylians. Crocodyliform science has grown appreciably the past few decades. New fossil species and genetic evidence continue to keep phylogenies and our understanding of relationships wavering in key places of the tree such as the relationships of the extinct marine thalattosuchians as well as still living species like gharials. The application of imaging approaches and 3D modeling to both preserved tissues as well as living specimens is now revealing patterns in brain and lung evolution and function, growth strategies, and feeding and locomotor behaviors across the lineage. Comparative anatomical studies are offering new data on genitals, cephalic venous drainage and thoracoabdominal pressures. The new discoveries found here only reveal there is far more work to be done to understand the biology and behavior responsible for the great radiation extinct suchians and their crocodylian descendants experienced during their conquest of Mesozoic and Tertiary ecosystems.
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