Leonhardtina

from Wikipedia, the free encyclopedia
Leonhardtina
Lower jaw of Leonhardtina

Lower jaw of Leonhardtina

Temporal occurrence
Lower to Middle Eocene ( Ypresian to Lutetian )
50.7 to 43.4 million years
Locations
Systematics
Higher mammals (Eutheria)
Laurasiatheria
Ferae
Hyaenodonta
Hyaenodontidae?
Leonhardtina
Scientific name
Leonhardtina
Matthes , 1952

Leonhardtina is a genus from the extinct order of the Hyaenodonta . It occurred in the late Lower Eocene and during the Middle Eocene around 51 to 43 million years ago. Fossil finds aredocumentedfrom the Geiseltal and the Paris Basin , among others. These are almost exclusively the remains of the lower jaw and teeth. The delicate structure of the lower jaw is striking. Relatively small animals can be inferred from the size of the finds. The exact relationship of Leonhardtina within the Hyaenodonta is under discussion. The genus was introduced in 1952.

description

Leonhardtina is a small representative of the Hyaenodonta. According to calculations, the body weight of smaller individuals was around 850 g, while larger individuals probably reached a maximum of 3 kg. Mainly remains of the lower jaw and isolated teeth have survived, parts of the skull are only a few. The latter have hardly any diagnostic features. The lower jaw was built very slim and had an extremely low horizontal bone body. Its height was about 1.4 cm below the first molar in large individuals. The symphysis at the anterior end extended to the middle of the second premolar . A mental foramen was formed on the outside below the first or second premolar or below the third premolar . The angular process started very low, as did the masseteric fossa on the outer surface of the ascending branch. The front edge of the ascending branch rose steeply behind the last molar at an angle of 70 °. The crown process sat 3.5 cm above the occlusal plane of the lower teeth. The joint on the articular process for connection with the skull had a cylindrical shape with the main axis transverse to the longitudinal direction of the lower jaw, its extension was 1.4 cm.

The upper dentition is incompletely covered with individual premolars and the molars. There were three incisors , one canine , four premolars and three molars per half in the lower jaw . The upper molars were wider than they were long, and the feature increases in clarity towards the rear. Characteristic of hyaenodonts, three main cusps rose on the chewing surface, which include the paraconus, the metaconus and the protoconus. The former two were positioned close together, but, unlike the representatives of the Hyaenodontidae, did not form a unit. In addition, the Paraconus towered over the Metaconus, while this is otherwise the case with the Hyaenodontidae. The three lower incisors were arranged side by side, the two outer teeth larger than the inner one. In addition to the respective pointed main hump, a small side hump was formed, creating a saw-like edge. The lower canine was rather small and had grooves on the surface. All of the lower premolars were longer than they were high, with the third exceeding the fourth in length. Similar evidence has also been found for Proviverra and Allopterodon . They each had a strong main hump, the protoconid, which under certain circumstances could be slightly asymmetrical. Each premolar tooth also had two roots. Short diastemas opened between the individual front molars . The three lower molars were almost the same length and comparatively low. The three main cusps, the Para-, Meta- and Protoconid, stood close together. The proto- and metaconid were almost the same size and only separated by a small furrow. The metaconide was only slightly reduced on the third molar. The lowest hump formed the paraconid. The talonid, a deeper depression that accommodated the protoconus of the maxillary molars when the bite was closed, was relatively wide, similar to that of Proviverra and Cynohyaenodon, and was also slightly longer than the trigonid with the three main tubercles. At the edge of the talonid there were several small side humps. On the last molar, the talonid was particularly long and narrow. The length of the lower molar row was 4.6 cm, of which the molars took up 1.85 cm.

Fossil finds

The most extensive fossil material to date from Leonhardtina is documented from the Geiseltal south of Halle in Saxony-Anhalt . The important fossil deposit dates to the Middle Eocene around 47 to 43 million years ago. The Geiseltal is a former mining area in which lignite was mined until the beginning of the 1990s . The coal deposits there comprised several seams, namely the base, lower, lower and upper middle and upper coal. Above all, the lower and middle coal proved to be fossil-bearing. The storage of fossils in carbonaceous layers can be considered a special feature among the Central European fossil sites. The finds consist of plants, invertebrates and vertebrates; they enable the reconstruction of a diverse community that developed under subtropical conditions relatively close to the coast. The landscape at that time consisted of a swamp area interspersed with flowing and still waters. 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), is particularly outstanding . Your include marsupials , various, often primitive insect-eating mammals, early primates , bats and predators and a form-rich cloven-hoofed animals - and Unpaarhufergemeinschaft on. The hyaenodonts form the second terrestrial predator group next to the predators . Several genera have been described, such as, in addition to Leonhardtina , also Matthodon , Eurotherium , Prodissopsalis and Oxyaenoides . Leonhardtina is one of the more common representatives with over a dozen finds. The finds come from the Lower Central Coal and date from 46 to 43 million years ago. They are distributed over various discovery areas within the seam, of which site VI in the Neumark-West mining field was particularly productive. The material consists of several lower jaws and a fragment of the palate; one of the remains of the lower jaw was also associated with an ankle bone . Other important sites are LII, LVIII and XXXVI as well as XXXVII, which also largely contained parts of the lower jaw. By contrast, individual skull remains were documented at sites I and XXXV.

Outside the Geiseltal valley, Leonhardtina has been found in Grauves, east of Paris, in the Paris Basin . The site is between 51 and 47 million years old, which corresponds to the end of the Lower Eocene. There is only a right lower jaw. Further finds were documented with an upper and lower jaw from Aumelas and another lower jaw from Rouzilhac , both in southern France.

Paleobiology

One of the Geiseltal lower jaws was associated with an ankle bone , which is similar to that of other hyaenodonta such as Sinopa , Limnocyon or Hyaenodon . It has a flat and asymmetrical surface on the back. The long neck is slightly narrowed, the joint head flattened above and below. There are only slight margins on the trochlea. The various joint facets, such as those for the navicular bone , the calcaneus or the fibula, are mostly prominent. The entire structure of the astragalus refers to a semi-plantigrade gait, in which the foot probably had great freedom of movement to the side.

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

Leonhardtina is a genus from the extinct order of the Hyaenodonta . The Hyaenodonta originally formed part of the Creodonta , some of which are somewhat misleading in German and also have the trivial designation "primal predators". These were classified as a sister group of today's predators (Carnivora) within the parent group of the Ferae . Phylogenetic studies showed the Creodonta to be a non-self-contained group. Therefore they were split into the Hyaenodonta and the Oxyaenodonta . For both groups, a pair of crushing shears that are shifted further back in the teeth compared to the predators is characteristic. In the hyaenodonts, the second upper and third lower molars are usually involved. The hyaenodonts first appeared in the Middle Paleocene around 60 million years ago; they last appeared in the Middle Miocene around 9 to 10 million years ago.

The first scientific description of Leonhardtina was carried out by Horst Werner Matthes in 1952. At that time, he had a left lower jaw branch (copy number GMH VI-42 / H / 10237) at which the row of teeth from the second premolar to the third molar and also the tooth sockets of the canine and the first premolar are located. It comes from site VI of the Neumark-West mining field. Is named Leonhard Tina to the Pit "New Leonhardt," the precise locality of reference VI. Due to the fine construction of the lower jaw named Matthes the nominate form with L. gracilis (from Latin gracilis for "slim" or "narrow"). Brigitte Lange-Badré and Hartmut Haubold undertook an extensive revision of the genus based on a large number of finds in 1990. Later, two more species were introduced with L. godinoti and L. meridianum . As a result, three types of Leonhardtina are known today:

L. godinoti is around 15 to 20% smaller than L. gracilis and was found in the Lower Eocene . The two types also differ in their tooth structure. Compared to the latter, the former has a larger third premolar and a longer talonid on the rearmost molar. The lower jaw of L. godinoti was presented as a remnant by Prototomus as early as 1971 . L. meridianum, on the other hand, is somewhat smaller than L. godinoti and has a very large third premolar. The species lived in the transition from the Lower to the Middle Eocene.

In his paper on the hyaenodonts of the Geiseltal from 1952, which also contains the first description by Leonhardtina , Matthes also set up the genus Geiselotherium with the species G. pilzi and G. robustum based on a lower jaw from site VI. In 1965, Leigh Van Valen questioned the validity of both Leonhardtina and Geiselotherium . He therefore synonymized Leonhardtina and in parts Geiselotherium ( G. pilzi ) with Proviverra (the larger form G. robustum put Van Valen to Prodissopsalis ). As a justification, he gave hardly any deviating tooth features between the three genera. Lange-Badré and Haubold, on the other hand, separated Leonhardtina from Proviverra in their revision of the now much more extensive Geiseltaler material , but kept G. pilzi with the former. In her opinion, some derived tooth features that do not appear in Proviverra speak for the independence of Leonhardtina . Both authors also stated that G. pilzi's description of the characteristics was based on some signs of wear and tear on the teeth, which Matthes erroneously assigned a taxonomic value.

The exact systematic allocation of Leonhardtina within the Hyaenodonta is currently assessed differently. In his first description, Matthes assigned the genus to the subfamily of the Proviverrinae and justified this with the pronounced metaconid on the lower molars. Van Valen confirmed this assessment by referring him to Proviverra . Leonhardtina formed the European branch of the group within the Proviverrinen together with other forms such as Matthodon or Eurotherium . The prominent metaconid on the molars of the lower jaw and the separation of the metaconus from the paraconus on those of the upper jaw can be highlighted as special characteristics of the Proviverrinen. Until the 1990s, the Proviverrinen were considered a largely generalized group within the Hyaenodonta, they initially included a larger part of the forms of the Lower and Middle Eocene. In the first phylogenetic studies, however, they then turned out to be paraphyletic and showed a more complex relationship. Therefore, in the following period, several authors tried to find a coherent structure of the Proviverrinae. Floreal Solé and colleagues spun off various subfamilies such as the Arfiinae, Sinopinae and Indohyaenodontinae in 2013 and 2014 and limited the Proviverrinae to an original, more European tribe. Because of the complex built premolars they ordered Leonhard Tina in a Allopterodon -Klade and also referred the genus to the side diminutive representatives as the eponymous Allopterodon or lesmesodon and Proviverra .

In contrast, a team of researchers led by Matthew R. Borths came to a different conclusion in 2016. The phylogenetic analyzes presented up to this point were largely based on locally localized finds. The research group therefore undertook a comprehensive study that included numerous taxa from North America, Africa and Eurasia. The scientists worked out a more detailed breakdown of the hyaenodonta. Regarding the Proviverrinae, some forms turned out to be more basal in the development of the Hyaenodonta, while others grouped themselves more strongly with representatives of the Hyaenodontidae family . As a result of their study, Borths and colleagues referred Leonhardtina to the Hyaenodontidae with a basal position within the group. Compared to the Proviverrinae, the Hyaenodontidae have a more specialized and tend to have hypercarnivoresic teeth. A striking feature can be found on the maxillary molars, in which the para- and metaconus are fused to form the amphiconus, the latter protruding above the former. Another expression of the hypercarnivorous properties of the teeth resulted, among other things, in the reduction of individual cusps, such as the metaconide on the lower molars. Leonhardtina has a separate para and metaconus, the metaconid is relatively well developed, but somewhat reduced on the last molar. This phylogenetic assessment was confirmed in a subsequent study from 2019.

literature

  • Brigitte Lange-Badré and Hartmut Haubold: Les créodontes (Mammifères) du gisement du Geiseltal (Eocène Moyen, RDA). Geobios 23 (5), 1990, pp. 607-637
  • Horst Werner Matthes: The Creodontier from the Middle Eocene brown coal of the Geiseltal. Hallesches Jahrbuch für Mitteldeutsche Erdgeschichte 1, 1952, pp. 201–240
  • 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 c d e f g 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
  2. ↑ Michael Morlo: Niche structure and evolution in creodont (Mammalia) faunas of the European an North American Eocene. Geobios 32 (2). 1999, pp. 297-305
  3. ↑ a b c d 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
  4. ↑ a b c d e f g Horst Werner Matthes: The Creodontier from the Middle Eocene brown coal of the Geiseltal. Hallesches Jahrbuch für Mitteldeutsche Erdgeschichte 1, 1952, pp. 201–240
  5. ↑ a b c d e f Brigitte Lange-Badré and Hartmut Haubold: Les créodontes (Mammifères) du gisement du Geiseltal (Eocène Moyen, RDA). Geobios 23 (5), 1990, pp. 607-637
  6. ↑ Hartmund Haubold: The reference fauna of the Geiseltalium, MP Levels 11 to 13 (Middle Eocene, Lutetian). Palaeovertebrata 19 (3), 1989, pp. 81-93
  7. ↑ 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
  8. ↑ 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
  9. ^ 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
  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. ^ A b Leigh Van Valen: Some European Proviverrini (Mammalia, Deltatheridia). Palaeontology 8, 1965, pp. 638-665
  17. ↑ 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
  18. ↑ 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 : Leonhardtina  - collection of images, videos and audio files