| Hauffiopteryx | |
|---|---|
 | |
| Fossil ofH. typicus | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | †Ichthyosauria |
| Node: | †Parvipelvia |
| Genus: | †Hauffiopteryx Maisch, 2008 |
| Type species | |
| †Hauffiopteryx typicus (von Huene, 1931 [originallyStenopterygius typicus]) | |
| Other species | |
| Synonyms | |
| |
Hauffiopteryx is anextinctgenus ofichthyosaur known fromGermany,Luxembourg,Switzerland andSomerset of theUnited Kingdom.[2][3][4] Two species are known:H. typicus andH. altera.
Hauffiopteryx was first described by Michael W. Maisch on the basis of some specimens that previously referred toStenopterygius hauffianus. Maisch found that the lectotype ofS. hauffianus can be determined asStenopterygius cf. S. quadriscissus at best, and therefore this species should be considered anomen dubium. He also found out that most specimens previously referred toS. hauffianus can be referred toS. quadriscissus, while the rest belongs to a highly distinctive new taxon that can't be referred to any valid species ofStenopterygius.[2]
Hauffiopteryx is known from thelectotypeGPIT 1491/4, articulated completeskeleton which preserved theskull and some soft tissues. The animal is about 1.93 m (6.3 ft) in length. It was collected from theHarpoceras elegantulum-exaratum ammonoid subzones (more specifically Lias ε II4),Harpoceras falcifer zone, of the famous Posidonien-Schieferlagerstätte (Posidonia Shale) ofHolzmaden, dating to the earlyToarcian stage of theEarly Jurassic, about 182million years ago. Referred specimens fromHolzmaden, Germany andDudelange, Luxembourg includeMHH '9', WAT 1,SMNS 51552, SMNS 80225 and probably the poorly preserved SMNS 81965. They were collected from theHarpoceras semicelatum-elegantulum-exaratum ammonoid subzones (Lias ε II1-5, about 182.7-181.8 mya),Harpoceras tenuicostatum-falcifer zones, of the Posidonia Shale.[2]
Additional materials were described by Hannah Caine andMichael J. Benton in 2011, from the early Toarcian ofStrawberry Bank,Ilminster of England. The specimens are all juveniles or infants which preserved almost complete skeletons and some skulls. They includeBRLSI M1399 (which was described earlier by Maisch), BRLSI M1400, BRLSI M1401, BRLSI M1403, BRLSI M1404 and BRLSI M1406.[3]
Hauffiopteryx was originally recognized byFriedrich von Huene in 1931 as a subspecies ofS. hauffianus and namedStenopterygius hauffianus typica. Michael W. Maisch in2008 elevated it to specific rank and reassigned to its own genus,Hauffiopteryx. Thetype species is thereforeHauffiopteryx typicus. Thegeneric name honors the Hauff family fromHolzmaden, for their generation-long work to increase the knowledge on the Posidonia Shale and its fauna, especially the ichthyosaurs, andpteryx (πτερυξ),Greek for "fin" or "wing". Thespecific name means typical.[2]H. altera comes from theLatin word meaning "different from" or "other" due to the differences between it andH. typicus.[1]
Hauffiopteryx is a relatively small ichthyosaur, reaching 2–3 m (6.6–9.8 ft) in length.[1][3]
The snout ofHauffiopteryx is short, but also very thin, tapering to a point.[3][1] The outer surface of thetooth crowns is smooth,[1] and the back teeth are larger than those in front.[3] The upper jaw is slightly longer than the lower jaw, though this overbite is not carried to the extreme seen inExcalibosaurus andEurhinosaurus.[3][1] Thenasals form the majority of the snout's midline, rather than thepremaxillae (upper tooth-bearing bones). InH. altera, the tallest points of themaxillae (rear upper tooth-bearing bones) are positioned behind theexternal nares (openings that housed the nostrils), in contrast toH. typicus, where the tallest points are instead located beneath these openings. Part of the borders of the external nares are formed by theprefrontals (paired bones situated on the upper edges of the eye sockets). InH. altera, this configuration blocks thelacrimals (paired bones in front of the eye sockets) from forming part of the external nares, whereas the lacrimals do reach the external nares inH. typicus. A further difference between the two species lies in the shape of their lacrimals; inH. typicus, they are triradiate, while those ofH. altera are massive and triangular.[1]
Theorbits (eye sockets) ofH. typicus are especially large and circular. In front of the orbits, the nasals ofH. typicus curve upwards. The nasals extend further back inH. altera than inH. typicus,[1] though the nasals ofHauffiopteryx do not touch theparietals (a pair of skull roof bones).[3] Externally, the prefrontals have greater surface area than thepostfrontals, especially so inH. altera.[1] Thefrontals (a pair of skull roof bones) form most of the border of thepineal foramen, a small opening on the midline of the skull.[3] Instead of being in line with the front edges of thesupratemporal fenestrae (paired openings on the top of the skull's rear), the foramen is instead located in front of them. The supratemporal fenestrae themselves are rounded and small. Thesupratemporals (paired skull roof bones) have wavy edges.[1] Behind the orbits, the skull is short from front to back, with the cheek region deflected so that it faces backwards. The rear facebasioccipital (braincase bone to which the vertebral column attaches) bears a considerable amount of surface which is not involved in the joint between the skull and the spine.[3]
In 2011, Caine and Benton stated thatHauffiopteryx has fewer than 46vertebrae in front of its hips (presacral vertebrae) and typically over 34 but under 39 between its hips and the bend in its tail.[3] Maxwell and Cortés in 2020 described the lectotype as having 45 or 46 presacral vertebrae and a total of 81 vertebrae before the bend in the tail (preflexural vertebrae), with this bend composed of three vertebrae followed by more than 55 postflexural vertebrae. The upper ends of the dorsalribs (those in the trunk region) are strongly forked, making them double-headed.Gastralia (belly ribs) are present along the underside of the trunk. This series of elements reaches far back, all the way to the level of the 35th vertebra.[1]
Thescapulae (shoulder blades) ofHauffiopteryx have wide lower ends due to their front margins extending forwards. The front edge of eachcoracoid (shoulder bones located below the scapulae) is concave. No space is enclosed between thehumeri (upper arm bones) and theradii andulnae (lower arm bones), being tightly packed together. This is also the case for the other bones in the upper parts of the limbs, forming amosaic-like pattern.[1] Each forelimb contains four main digits, and the front edge of the limb consists of some elements with indentations on their front edges. The lowerpelvic bones (thepubic bones andischia) are narrow and pillar-shaped. Unusually, the ends of these bones which form thehip socket are fused together, but the bones markedly diverge away from the socket. The thinfemora (thighbones) each bear a strong site for the articulation of thefibula (rear shin bone). The fibulae are also much larger than thetibiae (front shin bones). While the front edges of the hindlimbs contain some notched elements like the forelimbs, there are only three main digits in each rear limb.[3][1] These digits closely approach each other towards the tip of the limb.[1]
Both the original description by Maisch and the redescription of the English specimens found thatHauffiopteryx might be either abasalmost member ofEurhinosauria or a basalmost member ofThunnosauria (which is an equivalent position to a basalmost member ofStenopterygiidae sensu Maisch [2008] with exclusion ofIchthyosaurus).[3][2]
