Matthodon

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Matthodon
Lower jaw of Matthodon

Lower jaw of Matthodon

Temporal occurrence
Lower to Middle Eocene ( Ypresian to Lutetian )
50.7 to 46.3 million years
Locations
Systematics
Higher mammals (Eutheria)
Laurasiatheria
Ferae
Hyaenodonta
Hyaenodontidae?
Matthodon
Scientific name
Matthodon
Lange-Badré & Haubold , 1990

Matthodon is a genus of the extinct order Hyaenodonta . She lived in the late Lower and early Middle Eocene 51 to 46 million years ago in what is now Europe . Finds areprovenfrom the Paris basin and from the Geiseltal . These are largely parts of the lower jaw and individual teeth. The fossil remains indicate an approximately medium-sized predator . The specialized dentition allows a diet based on hard animal materials to be adopted. The exact systematic position of Matthodon within the Hyaenodonta is controversial. The genus was scientifically introduced in 1990.

description

Matthodon is a medium-sized representative of the Hyaenodonta, whose body weight is given as 12 to 30 kg. So far, mainly remains of the lower jaw and individual isolated teeth have been documented, only individual fragments of the upper jaw come from the skull. These have no diagnostic features. The lower jaw was robust and relatively short with a high horizontal bone body, the height of which, at 2.7 to 2.9 cm, hardly varied over the entire length. Likewise, the symphysis was high at the anterior end and extended to the third premolar. A mental foramen opened under both the second and third or fourth premolars . The ascending branch started directly behind the last tooth with no space for a gap. Its base was broad, on its outside there was a prominent and deep masseteric fossa as the attachment point for the masticatory muscle. The process of the crown loomed up.

Only the two posterior premolars and one middle molar of the upper dentition are clearly documented. The premolars had two or three roots and were dominated by a massive main hump, the paraconus. A total of three main cusps rose up on the molars, the para, meta and protoconus. The amphiconus typical of the Hyaenodontidae consisting of the paraconus and metaconus fused to one another did not occur. However, both humps were connected at the base. The Metaconus towered over the Paraconus, which has its counterpart in the representatives of the Hyaenodontidae. The protoconus was short and narrow. A prominent parastyle, a small side hump in front of the paraconus, settled on the front edge of the tooth. The lower dentition had two incisors , a canine , four premolars and three molars on each side of the jaw. The teeth were close together and there was no diastema . In this feature Matthodon differs from the simultaneous and similarly large Oxyaenoides . The canine was rather delicate in shape. In contrast, the premolars appeared noticeably voluminous, which again differs from Oxyaenoides . They were two-rooted except for the foremost, which had only one root. The individual tooth crowns were each shaped by a massive cusp, the protoconid, which looked somewhat asymmetrical in side view. However, the asymmetry decreased from front to back. Three main cusps, the para-, meta- and protoconid, rose on the chewing surfaces of the molars. The latter was the most developed. In contrast, the metaconide was greatly reduced in size. It finds its equivalent in Oxyaenoides . The talonid, a deeper part of the occlusal surface, which interlocks with the protoconus of the maxillary molars when the dentition closes, was short and wide compared to the trigonid with the three main cusps, its size decreased towards the last molar. Smaller humps occurred here, but they were only slightly developed. The length of the premolar row was up to 3.5 cm in larger individuals, that of the molars between 3.6 and 3.7 cm. The second molar, the largest tooth in the lower jaw, reached dimensions of up to 1.48 by 0.83 cm.

Fossil finds

Lower jaw from Matthodon from the Geiseltal

Significant fossil remains from Matthodon come from the Geiseltal south of Halle in Saxony-Anhalt . The Geiseltal is an outstanding fossil deposit that dates back to the Middle Eocene around 47 to 43 million years ago. As a former mining area , lignite was mined here until the beginning of the 1990s . Several coal seams were exposed, which are divided into the base, lower, lower and upper middle and upper coal. Above all, the lower and middle coal contained the fossil remains of the Geiseltal; the storage in the lignite can be seen as a special feature of the Central European fossil sites. They are made up of plants, invertebrates and vertebrates and allow a rich community to be reconstructed that existed under subtropical conditions relatively close to the coast. The landscape of that time can be reconstructed as a marsh area interspersed with flowing and still waters. Particularly noteworthy is the mammal fauna , which serves as a reference for the Geiseltalium , a stage within the stratigraphy of European land mammals ( European Land Mammal Ages , ELMA). Detected are marsupials , various, often primitive insect-eating mammals, early primates , bats and predators and a form-rich cloven-hoofed animals - and Unpaarhufergemeinschaft . In addition to the predators, the hyaenodonta also appeared as predators . Several species have been described, including plus to Matthodon also Eurotherium , Prodissopsalis , Oxyaenoides and Leonhard Tina . The finds from Matthodon can be assigned to the lower coal , based on which they are classified as 47 to 46 million years old. They were limited to site XIV in the Neumark-West mining field. Several mandibular fragments were found, two additional parts of the upper jaw could also belong to the genus.

In addition, other finds came to light at various sites such as Chavot, Monthelon, Cuis, Mancy, and Grauves north and east of Paris in the Paris Basin . With an age in the lower Eocene from 51 to 47 million years ago, they are somewhat older than those of the Geiseltal. The found material also consists largely of lower jaw fragments and individual teeth, plus a fragment of the upper jaw and connected to individual teeth of the upper dentition. Two more mandibles have been reported from Aumelas in southern France. Their age is in the transition from the Lower to the Middle Eocene.

Paleobiology

Due to the reduction of the metaconide, the Matthodon dentition loses its perforating properties compared to the early hyaenodonta and acquires a hypercarnivorous character. Today's hypercarnivorous predators feed on vertebrates for over 70% . The greatly enlarged premolars and the high body of the lower jaw are also striking. In a way, this creates similarities with today's hyenas . It is therefore believed that the animals ate hard materials such as bones mixed with meat. In addition, a partially digging way of life is assumed.

Systematics

Internal systematics of the Hyaenodontidae according to Solé & Mennecart 2019
  Hyaenodontoidea  
  Hyaenodontidae  



 Preregidens


   

 Leonhardtina



   


 Matthodon


   

 Oxyaenoides


   


 Thereutherium


   

 Prionogalidae



  Hyaenodontinae  

 Propterodon


   

 Hyaenodon






   


 Prodissopsalis


   

 Cartierodon



   

 Eurotherium





   
  " Cynohyaenodon clade"  


 Paracynohyaenodon


   

 Quercytherium



   

 Cynohyaenodon



   

 Boritia




   

 Proviverrinae



Template: Klade / Maintenance / Style

Matthodon is a genus from the extinct order of Hyaenodonta . The Hyaenodonta were once counted among the Creodonta , some of which were somewhat misleading, also bearing the trivial designation "primal carnivores " and were viewed as a sister group of today's carnivores within the higher-ranking group of the Ferae . 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 crushing shears that are shifted further back in the teeth compared to the predators . In the hyaenodonts, the second upper and third lower molars are usually involved. The first fossil record of the hyaenodonts dates back to the Middle Paleocene around 60 million years ago, while recent evidence is from the Middle Miocene around 9 to 10 million years ago.

The first scientific description of Matthodon was carried out by Brigitte Lange-Badré and Hartmut Haubold in 1990. It is based on the remains of the lower jaw from site XIV of the lower coal in the Geiseltal . They chose a right branch of the lower jaw as the holotype , in which the row of teeth from the first premolar to the last molar and the alveolus of the canine tooth have been preserved (copy number GMH XIV-739). The generic name Matthodon honors Horst Werner Matthes , former director of the Geiseltalmuseum, who had scientifically processed several Hyaenodonta from the type discovery site. Three types are recognized:

M. tritens represents the type from the Geiseltal. It is younger and about 12% larger than M. menui , and the metaconid of the lower molars is more strongly regressed. The latter species was introduced in 1971 by Thomas HV Rich under the name Oxyaena menui based on finds from the Paris basin . Rich assumed that the animals only had two molars and therefore referred the fossils to the Oxyaenodonta. Only in 2014 was it recognized that they belonged to Matthodon . M. peignei from southern France mediates between these two species both in size and in tooth design.

The exact systematic assignment of Matthodon within the Hyaenodonta is not clear and is evaluated differently. Lange-Badré and Haubold referred their new genus in the first description to the subfamily of the Proviverrinae . The genus was there together with other forms such as Leonhardtina and Eurotherium as a European branch of the group. Special features of the Proviverrin can be found in the prominent metaconid on the molars of the lower jaw and in the separation of the metaconus from the paraconus on those of the upper jaw. They were regarded as a largely generalized group within the Hyaenodonta until the 1990s and initially included a larger part of the forms of the Lower and Middle Eocene. However, in the first phylogenetic studies, they turned out to be paraphyletic with more complex relationships. In the period that followed, several authors tried to find a conclusive structure for the Proviverrinae. For example, in 2013 Floreal Solé and colleagues limited the Proviverrinae to an original, more European strain and separated out various other subfamilies such as the Arfiinae, the Sinopinae and the Indohyaenodontinae. Solé and colleagues looked Matthodon in 2014 therefore continue representing the Proviverrinae and referred the genre, highlighting the hypercarnivoren teeth coupled with the close position of the teeth in a separate clade ( Matthodon -Klade). However, a team of researchers led by Matthew R. Borths came to a different conclusion in 2016. Since the previous phylogenetic analyzes were based on locally delimited finds, they undertook a comprehensive study that included numerous taxa from North America, Africa and Eurasia. This led to a more broken down structure of the hyaenodonta. Some of the European Proviverrinae turned out to be very basal in the development of the Hyaenodonta, while others grouped themselves more strongly with representatives from the Hyaenodontidae family . Borths and colleagues therefore moved Matthodon to the Hyaenodontidae within which the genus occupies a more basic position. Compared to the Proviverrinae, the Hyaenodontidae are characterized by a more specialized and tending to hypercarnivore dentition. The para- and metaconus of the maxillary molars, which have grown together to form the amphiconus, are typical, with the latter protruding above the former. Another expression of the hypercarnivorous properties of the teeth was, among other things, the reduction of individual cusps such as the metaconid on the lower molars. In Matthodon , the para and metaconus are fused at the base, and the metaconid is also strongly regressed. The relatively basal position of Matthodon within the Hyaenodontidae could also be confirmed below.

literature

  • Brigitte Lange-Badré and Hartmut Haubold: Les créodontes (Mammifères) du gisement du Geiseltal (Eocène Moyen, RDA). Geobios 23 (5), 1990, pp. 607-637
  • Floréal Solé, Jocelyn Falconnet and Laurent Yves: New proviverrines (Hyaenodontida) from the early Eocene of Europe; phylogeny and ecological evolution of the Proviverrinae. Zoological Journal of the Linnean Society 171, 2014, pp. 878-917
  • Floréal Solé, Bernard Marandat and Fabrice Lihoreau: The hyaenodonts (Mammalia) from the French locality of Aumelas (Hérault), with possible new representatives from the late Ypresian. Geodiversitas 42 (13), 2020, pp. 185-214

Individual evidence

  1. ↑ a b Michael Morlo: Niche structure and evolution in creodont (Mammalia) faunas of the European an North American Eocene. Geobios 32 (2). 1999, pp. 297-305
  2. ↑ a b c d e f g h i j k Floréal Solé, Jocelyn Falconnet and Laurent Yves: New proviverrines (Hyaenodontida) from the early Eocene of Europe; phylogeny and ecological evolution of the Proviverrinae. Zoological Journal of the Linnean Society 171, 2014, pp. 878-917
  3. ↑ a b c d Brigitte Lange-Badré and Hartmut Haubold: Les créodontes (Mammifères) du gisement du Geiseltal (Eocène Moyen, RDA). Geobios 23 (5), 1990, pp. 607-637
  4. ↑ Hartmund Haubold: The reference fauna of the Geiseltalium, MP Levels 11 to 13 (Middle Eocene, Lutetian). Palaeovertebrata 19 (3), 1989, pp. 81-93
  5. ↑ Günter Krumbiegel, Ludwig Rüffle and Hartmut Haubold: The Eocene Geiseltal: a Central European brown coal deposit and its flora and fauna. Ziemsen, Wittenberg 1983, pp. 1-227
  6. ↑ Meinolf Hellmund: Excursion: Former Geiseltalrevier, southwest of Halle (Saale). From the Vita of the Eocene Geiseltal. In: Jörg Erfurt and Lutz Christian Maul (eds.): 34th meeting of the working group for vertebrate paleontology of the palaeontological society March 16-18, 2007 in Freyburg / Unstrut. Hallesches Jahrbuch für Geoswissenschaften BH 23, 2007, pp. 1–16
  7. ^ A b Thomas HV Rich: Deltatheridia, Carnivora, and Condylarthra (Mammalia) of the Early Eocene, Paris Basin, France. University of California Publications in Geological Sciences 88, 1971, pp. 1-72
  8. ↑ a b c Floréal Solé, Bernard Marandat and Fabrice Lihoreau: The hyaenodonts (Mammalia) from the French locality of Aumelas (Hérault), with possible new representatives from the late Ypresian. Geodiversitas 42 (13), 2020, pp. 185-214
  9. ↑ Floréal Solé and Sandrine Ladevèze: Evolution of the hypercarnivorous dentition in mammals (Metatheria, Eutheria) and its bearing on the development of tribosphenic molars. Evolution & Development 19 (2), 2017, pp. 56-68
  10. ↑ a b 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 (2), 2019, pp. 275–290, doi: 10.4202 / app.00581.2018
  11. ↑ Kenneth D. Rose: The beginning of the age of mammals. Johns Hopkins University Press, Baltimore, 2006, pp. 1–431 (pp. 122–126)
  12. ↑ 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
  13. ↑ 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
  14. ↑ Floréal Solé, Eli Amson, Matthew Borths, Dominique Vidalenc, Michael Morlo and Katharina Bastl: A New Large Hyainailourine 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
  15. ↑ 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
  16. ↑ 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
  17. ↑ Rajendra S. Rana, Kishor Kumar, Shawn P. Zack, Floreal Solé, Kenneth D. Rose, Pieter Missiaen, Lachham Singh, Ashok Sahni and Thierry Smith: Craniodental and Postcranial Morphology of Indohyaenodon raoi from the Early Eocene of India, and Its Implications for Ecology, Phylogeny, and Biogeography of Hyaenodontid Mammals. Journal of Vertebrate Paleontology 35 (5), 2015, p. E965308, doi: 10.1080 / 02724634.2015.965308

Web links

Commons : Matthodon  - collection of images, videos and audio files