Forehead shield
| f ag in l la la´ m n p | Frontal anterior chin shields Internasals Loreal Supralabials Sublabials Mentale Nasalia Parietalia | pf pg pro pso pto r so t v | Präfrontalia Rear chin shields Präoculare Präsuboculare Postocularia rostral Supraoculare Front and rear Temporalia First Anterior |
A horny scale on the head of a scale lizard (Lepidosauria) is usually referred to as the forehead shield . The Latin term is Scutum frontale or the frontale for short . Like all dandruff, the frontal can be important in determining the species .
In birds , a so-called forehead shield (also frontal shield) can be pronounced as part of the beak and - as in some species of railings - cover the forehead or part of it. One example is the coot , where the white forehead shield can vary in size depending on the season, age and gender.
Forehead shield of the scaled lizards
Character and location
If you look at the head from above, the forehead shield is at eye level and, depending on the type, can be directly adjacent to the scales above the eye ( supraoculars ). Caudally , i.e. in the direction of the tail, the forehead shield borders on the parietal shields (Scutum parietale) and, if present, as in the Iberian roller skink (Chalcides bedriagai) , on the interdental shields (Scutum interparietale). Rostral, in the direction of the snout, borders the frontal shield on the prefrontals , so the "forehead shields".
Many species of snakes have a single frontal. Other species have two frontal shields that are usually symmetrical to the snout-tail axis. One then speaks of a divided frontal. As with many vipers (Viperidae) but also with the Angolapython (Python anchietae) , the head shields can also be broken up into many small scales.
The reddish-beaked snake ( Rhamphiophis oxyrhynchus ) has an undivided forehead shield.
Aipysurus laevis has a split frontal shield.
In the adder (Vipera berus) the frontal does not border directly on the supraocular.
In the green-yellow palm lance viper (Bothriechis lateralis) , all of the scales on the top of the head are broken up into small individual scales.
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The shape and form of the front shields serve to differentiate between species, but at least above the genus level, a close relationship cannot generally be inferred from similar front shields. The following examples show this:
- Stoliczkia borneensis , a humpback snake , and Aipysurus laevis , a sea snake (Hydrophiinae), both have a split frontal. Achalinus spinalis , also a humpback snake , and the adder flattail (Laticauda colubrina) , again a sea snake, both have an undivided frontal.
- In the family of the vipers (Viperidae) the European horned viper (Vipera ammodytes) and the green-yellow palm lance viper (see above) have dissolved head shields. The adder (Vipera berus) and the Chinese nosed viper (Deinagkistrodon acutus) , on the other hand, have pronounced forehead shields, although the adder is more closely related to the horned viper - both belong to the subfamily of the real vipers (Viperinae) - and the Chinese nosed viper like the green and yellow palm lance viper to the Pit vipers (Crotalinae) heard.
See also
literature
- Bruno Dürigen : Germany's amphibians and reptiles: A description and portrayal. Creutz'sche Verlagbuchhandlung, 1897.
Individual evidence
- Jump up ↑ Barry Taylor, Ber van Perlo: Rails - A Guide to the Rails, Crakes, Gallinules and Coots of the World , Pica Press, The Banks, Mountfield 1998, ISBN 1-873403-59-3 , pp. 25 and 33, German Designation "forehead shield" in Urs N. Glutz von Blotzheim , KM Bauer: Handbook of the birds of Central Europe , Volume 5, Galliformes - Gruiformes, chicken birds, railing and crane birds, AULA-Verlag, ISBN 3-923527-00-4 .
- ↑ Illustration by Rooij, Nelly de: Fig 26. Stoliczkaia borneensis Blg. In: The reptiles of the Indo-Australian archipelago. Volume 2. Leiden 1915.
- ↑ Illustration by Takahashi: Juvenile Japanese Odd-scaled Snake, Achalinus spinalis.
- ^ Illustration by MA Smith: Laticauda colubrina. In: Fauna of British India. Reptilia and Batrachia. 1941-1943.
- ↑ Figure by H. Krisp: Horned Viper Vipera ammodytes ruffoi.
- ↑ illustration of Danleo: Sharp-Nosed Viper at Wilmington's Serpentarium.