Cartierodon
| Cartierodon | ||||||||||||
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Cartierodon's teeth and dentition remnants (L represents the holotype ) |
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| Temporal occurrence | ||||||||||||
| Middle Eocene | ||||||||||||
| 47.8 to 41.3 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Cartierodon | ||||||||||||
| Solé & Mennecart , 2019 | ||||||||||||
Cartierodon is a genus from the extinct group of Hyaenodonta . It is known from teeth and individual remains of teeth from the fossil deposit of Egerkingen in Switzerland. The material recovered there belongs to the Middle Eocene and dates from 48 to 41 million years ago. Based on the teeth, a comparatively large representative of the hyaenodonta can be inferred, which was one of the largest of its time. The animals possibly fed as scavengers and could bite bones with their strong teeth. The genus was scientifically introduced in 2019 with a species.
features
Cartierodon is a medium-sized representative of the Hyaenodonta. So far, mainly isolated teeth plus individual jaw fragments have been handed down. This also includes the lower jaw. Its horizontal bone body was comparatively deep at around 3.6 cm. The symphysis at the anterior end, connecting the two branches of the jaw, extended to the third premolar . An anterior mental foramen opened below the second, and a rear one below the fourth premolar. The position of the two foramina agrees with Matthodon , but differs from Prodissopsalis , which had only one such bone opening. So far, only the molars of the Cartierodon dentition are available, the front teeth are unknown. The first premolar had two roots in both the lower and the upper row of teeth, the following had three each. In the upper dentition, there was a short tooth gap between the first and second premolars . The upper premolars were characterized by a high main cusp, the paraconus. At the rear, the metastyle was followed by a shear bar that was only designed for a short time. An anterior cutting ridge, the parastyle, was absent on the first three premolars, but occurred on the fourth. The very short but wide talonid (a deeper lying area of the chewing surface of the teeth) was noticeable on the lower premolars. The resulting widened premolars find their equivalent in Matthodon . In contrast to these, the premolars in Cartierodon were less voluminous. In the latter aspect, there are again similarities with Prodissopsalis . Three main cusps dominated the upper molars (para-, meta- and protoconus). The two cusps on the cheek side, the para and metaconus, were fused together, but the respective tips were still visible as separate units. Typically for the members of the Hyaenodontidae, the Metaconus towered over the Paraconus. The metastyle was extremely long and corresponded to the basal length of the para and metaconus. The lower molars also had three main cusps (Para-, Meta- and Protoconid), the Metaconid was, like many representatives of the Hyaenodontidae, greatly reduced in size. The reduction of the metaconide was, however, not as advanced as in Paenoxyaenoides . Individual smaller side humps appeared on the short talonid. The length of the molars varied between 1.2 and 1.7 cm in the upper and lower dentition, the width between 0.7 and 1.0 cm (in the lower dentition).
Fossil finds
The previously available find material from Cartierodon was recovered in the important Swiss fossil deposit of Egerkingen (Canton Solothurn ). The site consists of three karst fissures filled with ferrous clays , which are designated as "α", "β" and "γ". The very extensive finds embedded in it were already excavated in the middle of the 19th century. It received extensive scientific attention through several extensive publications. The collection not only contained several representatives of the hyaenodonts, it gained additional significance through various forms of primates such as Caenopithecus or forms more or less closely related to them such as Heterohyus . In addition, remains of birds came to light. The majority of the slightly more than 30 found objects that are assigned to Cartierodon come from the column filling "γ". For biostratigraphic reasons, their fauna is classified as somewhat older than that of the column fillings "α" and "β". However, all three find complexes are dated to the lower section of the Middle Eocene , so the absolute age is 48 to 41 million years.
In addition to the finds from Egerkingen, individual teeth from Lissieu north of Lyon in France are considered possibly belonging to the genus. As with Egerkingen, Lissieu is an extensive crevice filling that was unearthed during quarrying work in the 19th century.
Paleobiology
Since Cartierodon has so far largely been found of teeth and jaw remains , statements on paleobiology are only possible to a limited extent. Various methods can be used to determine the height of predatory mammals, some of which rely on the dimensions of the teeth. Taking into account the average size of the teeth of the crushing scissors , a weight of around 29 kg can be assumed for Cartierodon . The genus was thus larger than the similarly old Matthodon from the Geiseltal . It is one of the largest known hyaenodonts from the period of the early Middle Eocene ( Lutetium ). It was not until the subsequent late Middle Eocene ( Bartonian ) that a significantly larger representative of the hyaenodonta appeared in western Europe with Kerberos , whose weight was determined to be around 85 to 90 kg using the same method (140 to 277 kg are also possible according to other methods) . Due to its size , Cartierodon may only have competed with a few large predatory ratites such as Eleutherornis or various representatives of crocodiles in the respective biotope .
The diet can also be partially read from the teeth. In addition to the massive body of the lower jaw, the relatively large premolars, which are largely closed without being interrupted by a large diastema , are striking . The molars are characterized by the three large cusps that occupy a larger part of the chewing surface of the teeth. All of these characteristics speak in favor of a diet based largely on meat and bones. With that, Cartierodon could be classified as a scavenger . Due to the large premolars, there are similarities to today's hyenas , who break the bones with the help of their premolar teeth, in contrast to the wolf , who uses the rearmost teeth following the breaker for this.
Systematics
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Internal systematics of the Hyaenodontidae according to Solé & Mennecart 2019
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Cartierodon is a genus from the extinct order of Hyaenodonta . Originally the Hyaenodonta belonged to the group of Creodonta , which in German carry the sometimes somewhat misleading trivial designation "primal predators". They were once considered a sister group of today's carnivores within the higher-ranking taxon of the Ferae . After several identical phylogenetic examinations, however, the Creodonta turned out to be a non-self-contained group and were ultimately split into the Hyaenodonta and the Oxyaenodonta . Both groups are characterized by a pair of crushing shears that are moved further back in the teeth compared to the predators . In the hyaenodonts, the second upper and third lower molars are usually involved. The hyaenodonts can be found fossilized as early as the Middle Paleocene around 60 million years ago, young specimens come from the Middle Miocene around 9 to 10 million years ago.
Due to the special tooth structure, Cartierodon can be placed within the Hyaenodonta family of the Hyaenodontidae . The Hyaenodontidae have a relatively highly specialized set of teeth, the characteristic of which is the para- and metaconus of the maxillary molars that have grown together to form the amphiconus. The Metaconus towers over the Paraconus, which in turn distinguishes the Hyaenodontidae from the Hyainailouridae , the second major line of development within the Hyaenodonta. Furthermore, the molars of the Hyaenodontidae show tendencies towards hypercarnivory, which is expressed, among other things, in the reduction of individual cusps such as the metaconid on the lower molars. Both features can be demonstrated in Cartierodon . Within the Hyaenodontidae, Cartierodon is relatively basal in the line of development. Prodissopsalis and Eurotherium can be classified as closely related, and Matthodon and Leonhardtina are also presumably to be classified in a closer relationship. All four named forms were documented from the approximately same age deposits of the Geiseltal , whereby Eurotherium and Matthodon have a somewhat earlier occurrence ( lower coal ) than Prodissopsalis and Leonhardtina (middle coal). The latter is closer in time to the well-known appearance of Cartierodon in Egerkingen.
The genus Cartierodon was first scientifically described in 2019 by Floréal Solé and Bastien Mennecart . The found material from the Swiss fossil deposit in Egerkingen served as the basis . The authors determined the holotype with a right lower jaw fragment (copy number: NMB .Em.11), which still contains the row of teeth from the second to fourth premolars , the partially preserved first molars and the alveolus of the first premolar. The name Cartierodon was already used by Brigitte Lange-Badré in the early 1970s when she was intensively studying the hyaenodont material at the Natural History Museum in Basel. However, she never used it in a publication, but only noted it in individual find descriptions. It refers to the pastor Robert Cartier, who carried out excavations in Egerkingen in the second half of the 19th century. The second syllable of the name odon is of Greek origin ( οδούς ) and means something like "tooth". The only species named was C. egerkingensis , which Solé and Mennecart also took over from Lange-Badré. The specific epithet egerkingensis refers to the type finding place.
literature
- Floréal Solé and Bastien Mennecart: A large hyaenodont from the Lutetian of Switzerland expands the body mass range of the European mammalian predators during the Eocene. Acta Palaeontologica Polonica 64, 2019, doi: 10.4202 / app.00581.2018
Individual evidence
- ↑ a b c d e f g h Floréal Solé and Bastien Mennecart: A large hyaenodont from the Lutetian of Switzerland expands the body mass range of the European mammalian predators during the Eocene. Acta Palaeontologica Polonica 64, 2019, doi: 10.4202 / app.00581.2018
- ↑ Leopold Riitimeyer: Eocene mammals in the area of the Swiss Jura. New memoranda of the Swiss Society for the Whole Natural Sciences 19, 1862, pp. 1–98
- ↑ Hans Georg Stehlin: The mammals of the Swiss Eocaens. Critical catalog of materials. Treatises of the Swiss Paleontological Society 56, 1916, pp. 1209–1556 (pp. 1434–1508)
- ↑ Eric R. Seiffert, Loic Costeur and Doug M. Boyer: Primate tarsal bones from Egerkingen, Switzerland, attributable to the Middle Eocene adapiform Caenopithecus lemuroides. PeerJ 3, 2015, p. E1036, doi: 10.7717 / peerj.1036
- ↑ Delphine Angst, Eric Buffetaut, Christophe Lécuyer and Romain Amiot: “Terror birds” (Phorusrhacidae) from the Eocene of Europe imply trans-Tethys dispersal. PLoS ONE 8 (11), 2013, p. E80357, doi: 10.1371 / journal.pone.0080357
- ↑ Michael Morlo and Jörg Habersetzer: The Hyaenodontidae (Creodonta, Mammalia) from the Lower Eocene (MP 11) of Messel (Germany) with special remarks on new x-ray methods. Courier Forschungsinstitut Senckenberg 216, 1999, pp. 31–73
- ↑ a b c Floréal Solé, Eli Amson, Matthew Borths, Dominique Vidalenc, Michael Morlo and Katharina Bastl: A new large hyainailourinae from the Bartonian of Europe and its bearings on the evolution and ecology of massive hyaenodonts (Mammalia). PLoS ONE 10 (9), 2015, p. E0135698, doi: 10.1371 / journal.pone.0135698
- ↑ Kenneth D. Rose: The beginning of the age of mammals. Johns Hopkins University Press, Baltimore, 2006, pp. 1–431 (pp. 122–126)
- ↑ Michael Morlo, Gregg Gunnell, and P. David Polly: What, if not nothing, is a creodont? Phylogeny and classification of Hyaenodontida and other former creodonts. Journal of Vertebrate Paleontology 29 (3 suppl), 2009, p. 152A
- ↑ Floréal Solé: New proviverrine genus from the Early Eocene of Europe and the first phylogeny of Late Paleocene-Middle Eocene hyaenodontidans (Mammalia). Journal of Systematic Paleontology 11, 2013, pp. 375-398
- ↑ a b Matthew R. Borths, Patricia A. Holroyd and Erik R. Seiffert: Hyainailourine and teratodontine cranial material from the late Eocene of Egypt and the application of parsimony and Bayesian methods to the phylogeny and biogeography of Hyaenodonta (Placentalia, Mammalia). PeerJ 4, 2016, p. E2639 doi: 10.7717 / peerj.2639
