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Haldanodon

Haldanodon is an extinct docodont mammaliaform which lived in the Upper Jurassic (Kimmeridgian, about 145 million years ago). Its fossil remains have been found in Portugal, in the well-known fossil locality of Guimarota, which is in the Alcobaça Formation. It may have been a semi-aquatic burrowing insectivore, similar in habits to desmans and the platypus. Several specimens are known, include a partial skeleton and well-preserved skulls.[1][2]

Haldanodon
Temporal range: Kimmeridgian, 145 Ma
Molar teeth in occlusal view (left) and medial view (right)
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Therapsida
Clade: Cynodontia
Clade: Mammaliaformes
Order: Docodonta
Family: Docodontidae
Genus: Haldanodon
Kühne & Krusat, 1972
Species:
H. exspectatus
Binomial name
Haldanodon exspectatus
Kühne & Krusat, 1972

Description edit

Haldanodon was about as long as a desman, and may have had a similar ecology. The skull was low and triangular when seen from above. For many years it had the best-known skull material of any docodont, making it vital for understanding the taxonomic position of that mammaliaform group. It was the first Mesozoic mammaliaform discovered to possess turbinal plates, a complex feature of mammalian nasal cavities. However, it also retained some curiously primitive traits in common with non-mammaliaform cynodonts.[1]

The body was compact and the legs were short and robust. The articulation of the distal humerus was particularly expanded, indicating strong muscles for either digging or swimming. The front paws were relatively short, and the bones of the forelimb were curved and laterally compressed.[2]

Classification edit

Haldanodon was a docodont, part of a group of Jurassic to Cretaceous early mammaliaforms with specialized teeth[3] The docodonts were widespread in Laurasia, and show an interesting diversity of ecological lifestyles unknown in other Mesozoic mammaliaforms. Haldanodon is specifically considered a docodontid, and has been found as the sister taxon to Docodon in many analyses.[3]

Phylogeny[4]

Paleobiology edit

Haldanodon may have been a fossorial (burrowing) and/or semi-aquatic insectivore, similar in lifestyle to the modern desmans and Ornithorhynchus (the duck-billed platypus). This is indicated by some skeletal features, such as a wide scapula and stout limb bones with specialized joints. It likely had a sprawling gait based on the configuration of its limb joints, but this is probably a result of its specialized lifestyle instead of a primitive trait. The fingers and claws of the forelimb seem to correspond closely to scratch-digging modern mammals like armadillos and pangolins, rather than shovel-diggers like moles.[2]

References edit

  1. ^ a b Lillegraven, Jason A.; Krusat, Georg (1991-10-01). "Cranio-mandibular anatomy of Haldanodon exspectatus (Docodonta; Mammalia) from the late Jurassic of Portugal and its implications to the evolution of mammalian characters" (PDF). Rocky Mountain Geology. 28 (2): 39–138. ISSN 1555-7332.
  2. ^ a b c Martin, Thomas (2005-10-01). "Postcranial anatomy of Haldanodon exspectatus (Mammalia, Docodonta) from the Late Jurassic (Kimmeridgian) of Portugal and its bearing for mammalian evolution". Zoological Journal of the Linnean Society. 145 (2): 219–248. doi:10.1111/j.1096-3642.2005.00187.x. ISSN 0024-4082.
  3. ^ a b Luo Z-X and Martin T. 2007. Analysis of molar structure and phylogeny in docodont genera. Bulletin of Carnegie Museum of Natural History.
  4. ^ Close, Roger A.; Friedman, Matt; Lloyd, Graeme T.; Benson, Roger BJ (2015). "Evidence for a mid-Jurassic adaptive radiation in mammals". Current Biology. 25 (16): 2137–2142. doi:10.1016/j.cub.2015.06.047. PMID 26190074.

Further reading edit

  • Kühne & Krusat (1972), Legalisierung des taxon Haldonodon (Mammalia, Docodonta)
  • Neues Jahrbuch für Geologie, Paläontologie and Mineralogie, Monatshefte 5, P.300-302
  • Martin T & M Nowotny (2000), The docodont Haldanodon Guimarota from the mines, p. 91-96
  • Martin T & Krebs B (eds), Guimarota - A Jurassic Ecosystem, Verlag Dr. Friedrich Pfeil, München

haldanodon, extinct, docodont, mammaliaform, which, lived, upper, jurassic, kimmeridgian, about, million, years, fossil, remains, have, been, found, portugal, well, known, fossil, locality, guimarota, which, alcobaça, formation, have, been, semi, aquatic, burr. Haldanodon is an extinct docodont mammaliaform which lived in the Upper Jurassic Kimmeridgian about 145 million years ago Its fossil remains have been found in Portugal in the well known fossil locality of Guimarota which is in the Alcobaca Formation It may have been a semi aquatic burrowing insectivore similar in habits to desmans and the platypus Several specimens are known include a partial skeleton and well preserved skulls 1 2 HaldanodonTemporal range Kimmeridgian 145 Ma PreꞒ Ꞓ O S D C P T J K Pg N Molar teeth in occlusal view left and medial view right Scientific classification Domain Eukaryota Kingdom Animalia Phylum Chordata Clade Synapsida Clade Therapsida Clade Cynodontia Clade Mammaliaformes Order Docodonta Family Docodontidae Genus HaldanodonKuhne amp Krusat 1972 Species H exspectatus Binomial name Haldanodon exspectatusKuhne amp Krusat 1972 Contents 1 Description 2 Classification 3 Paleobiology 4 References 5 Further readingDescription editHaldanodon was about as long as a desman and may have had a similar ecology The skull was low and triangular when seen from above For many years it had the best known skull material of any docodont making it vital for understanding the taxonomic position of that mammaliaform group It was the first Mesozoic mammaliaform discovered to possess turbinal plates a complex feature of mammalian nasal cavities However it also retained some curiously primitive traits in common with non mammaliaform cynodonts 1 The body was compact and the legs were short and robust The articulation of the distal humerus was particularly expanded indicating strong muscles for either digging or swimming The front paws were relatively short and the bones of the forelimb were curved and laterally compressed 2 Classification editHaldanodon was a docodont part of a group of Jurassic to Cretaceous early mammaliaforms with specialized teeth 3 The docodonts were widespread in Laurasia and show an interesting diversity of ecological lifestyles unknown in other Mesozoic mammaliaforms Haldanodon is specifically considered a docodontid and has been found as the sister taxon to Docodon in many analyses 3 Phylogeny 4 Mammaliaformes Adelobasileus Sinoconodon Morganucodon Megazostrodon Haramiyida Haldanodon Castorocauda Hadrocodium MammaliaPaleobiology editHaldanodon may have been a fossorial burrowing and or semi aquatic insectivore similar in lifestyle to the modern desmans and Ornithorhynchus the duck billed platypus This is indicated by some skeletal features such as a wide scapula and stout limb bones with specialized joints It likely had a sprawling gait based on the configuration of its limb joints but this is probably a result of its specialized lifestyle instead of a primitive trait The fingers and claws of the forelimb seem to correspond closely to scratch digging modern mammals like armadillos and pangolins rather than shovel diggers like moles 2 References edit a b Lillegraven Jason A Krusat Georg 1991 10 01 Cranio mandibular anatomy of Haldanodon exspectatus Docodonta Mammalia from the late Jurassic of Portugal and its implications to the evolution of mammalian characters PDF Rocky Mountain Geology 28 2 39 138 ISSN 1555 7332 a b c Martin Thomas 2005 10 01 Postcranial anatomy of Haldanodon exspectatus Mammalia Docodonta from the Late Jurassic Kimmeridgian of Portugal and its bearing for mammalian evolution Zoological Journal of the Linnean Society 145 2 219 248 doi 10 1111 j 1096 3642 2005 00187 x ISSN 0024 4082 a b Luo Z X and Martin T 2007 Analysis of molar structure and phylogeny in docodont genera Bulletin of Carnegie Museum of Natural History Close Roger A Friedman Matt Lloyd Graeme T Benson Roger BJ 2015 Evidence for a mid Jurassic adaptive radiation in mammals Current Biology 25 16 2137 2142 doi 10 1016 j cub 2015 06 047 PMID 26190074 Further reading editKuhne amp Krusat 1972 Legalisierung des taxon Haldonodon Mammalia Docodonta Neues Jahrbuch fur Geologie Palaontologie and Mineralogie Monatshefte 5 P 300 302 Martin T amp M Nowotny 2000 The docodont Haldanodon Guimarota from the mines p 91 96 Martin T amp Krebs B eds Guimarota A Jurassic Ecosystem Verlag Dr Friedrich Pfeil Munchen Retrieved from https en wikipedia org w index php title Haldanodon amp oldid 1151291263, wikipedia, wiki, book, books, library,

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