Teinolophos trusleri was a prehistoric monotreme, or egg-laying mammal. It is known from a lower jawbone found in Flat Rocks, Victoria, Australia. It lived during the Aptian age of the Lower Cretaceous. The conservation status of a species is an indicator of the likelihood of that species continuing to survive. ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria Placozoa Bilateria Acoelomorpha Orthonectida Rhombozoa Myxozoa Superphylum Deuterostomia    Chordata (vertebrates, etc. ... Typical Classes Subphylum Urochordata - Tunicates Ascidiacea Thaliacea Larvacea Subphylum Cephalochordata - Lancelets Subphylum Myxini - Hagfishes Subphylum Vertebrata - Vertebrates Petromyzontida - Lampreys Placodermi (extinct) Chondrichthyes - Cartilaginous fishes Acanthodii (extinct) Actinopterygii - Ray-finned fishes Actinistia - Coelacanths Dipnoi - Lungfishes Amphibia - Amphibians Reptilia - Reptiles Aves - Birds Mammalia - Mammals Chordates (phylum Chordata) include the vertebrates, together with... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... Families Kollikodontidae (extinct) Ornithorhynchidae - Platypus Tachyglossidae - Echidnas Steropodontidae (extinct) Monotremes (< monos, single + trema, hole; refers to the cloaca) are mammals that are best known for laying eggs, instead of giving birth to live young like marsupials and placental mammals (Eutheria). ... In biology, binomial nomenclature is a standard convention used for naming species. ... Families Kollikodontidae (extinct) Ornithorhynchidae - Platypus Tachyglossidae - Echidnas Steropodontidae (extinct) Monotremes (< monos, single + trema, hole; refers to the cloaca) are mammals that are best known for laying eggs, instead of giving birth to live young like marsupials and placental mammals (Eutheria). ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... Motto: Peace and Prosperity Nickname: Garden State Other Australian states and territories Capital Melbourne Government Governor Premier Const. ... The Cretaceous period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic period (about 135 mya) to the beginning of the Paleocene epoch of the Tertiary period (65 mya). ...

The species name honours the artist Peter Trusler. The genus name, Teinolophos, means 'extended ridge', a reference to its tooth structure. In biology, a species is a kind of organism. ... See genus (mathematics) for the use of the term in mathematics. ...

Originally, Teinolophos was thought to be a eupanthothere. Further research revealed similarities to Steropodon, except in size: the animal was around 10 cm long. Binomial name Steropodon galmani Steropodon was a prehistoric monotreme, or egg-laying mammal that lived during the middle Albian era, in the Lower Cretaceous period. ...

The holotype is a partial left dentary known as NMV P208231. An age of approximately 123 million years makes this the earliest known monotreme. The lower molar is broadly similar in morphology to the m2 of Steropodon. The trigonid is compressed and the talonid has no basin. The dentary is about one sixth the size of Steropodon's, and wear facets indicate an "orthal" occlusion with the upper molars. A holotype (sometimes simply type) is the single physical example or illustration of an organism that defines the characteristics of the whole species. ... The dentary is the tooth bearing bone of the lower jaw. ... Families Kollikodontidae (extinct) Ornithorhynchidae - Platypus Tachyglossidae - Echidnas Steropodontidae (extinct) Monotremes (< monos, single + trema, hole; refers to the cloaca) are mammals that are best known for laying eggs, instead of giving birth to live young like marsupials and placental mammals (Eutheria). ... The molar design that is considered one of the most important characteristics of mammals is a three-cusped shape called a tribosphenic molar. ... The molar design that is considered one of the most important characteristics of mammals is a three-cusped shape called a tribosphenic molar. ...

The construction of the lower jaw differs from existing monotremes. Among the contrasts are the condyle, which is well above the tooth row (instead of at about the same height); and the ascending ramus, which is also higher. Also different is that Teinolophos probably had a strong bite. A unique feature for known toothed monotremes is that the trigonid is tall, while the talonid is set much lower. This is more like the general mammalian arrangement. The molar is double-rooted, which is plesiomorphic when compared to ornithorhynchids, but is a shared characteristic with Steropodon and Kollikodon. Subsequent monotreme molars are multi-rooted. Categories: Move to Wiktionary | Anatomy stubs ... Binomial name Ornithorhynchus anatinus Shaw, 1799 The platypus (Ornithorhynchus anatinus) is a small, semi-aquatic mammal endemic to the eastern part of Australia, and one of the four extant monotremes, the only mammals that lay eggs instead of giving birth to live young (the other three are echidnas). ... Kollikodon is an extinct species of Monotreme. ...

See also

• Fossil Monotremes

Families Kollikodontidae (extinct) Ornithorhynchidae - Platypus Tachyglossidae - Echidnas Steropodontidae (extinct) Monotremes (< monos, single + trema, hole; refers to the cloaca) are mammals that are best known for laying eggs, instead of giving birth to live young like marsupials and placental mammals (Eutheria). ...

Links and References

• Rich et al. "Early Cretaceous Mammals from Flat Rocks, Victoria, Australia". Records of the Queen Victoria Museum, Launceston (1999).
• Rich, T. H., et al. "Monotreme nature of the Australian Early Cretaceous mammal Teinolophos". Acta Palaeontologica Polonica 46(1). 2001 Pages 113–118.
• Life in the Shadows, Non-reptilian life in Mesozoic Australia (http://www.alphalink.com.au/~dannj/non-rept.htm)
• Mesozoic Mammals: Monotremata, an Internet directory (http://home.arcor.de/ktdykes/monotrem.htm)