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Home , Ardeosaurus, Bavarisaurus, Eichstaettisaurus, Scleroglossa, Yabeinosaurus

PROGRESS IN NATURAL SCIENCE Vol .15 , N o .2 , F ebruary 2005

A new Early with well-preserved scale impressions from western Liaoning , China＊

JI Shu' an ＊＊

(S chool of Earth and S pace Sciences, Peking University , Beijing 100871 , China)

Received May 14 , 2004 ;revised September 29 , 2004

Abstract A new small lizard , Liaoningolacerta brevirostra gen .et sp .nov ., from the Early Cretaceous Yixian Formation of w estern Liaoning is described in detail.The new specimen w as preserved not only by the skeleton , but also by the exceptionally clear scale impressions.This lizard can be included w ithin the based on its 26 or more presacrals, cruciform interclavicle with a large anterior p rocess, moderately elongated , and slightly notched distal end of tibia .The scales vary evidently in size and shape at different parts of body :small and rhomboid ventral scales, tiny and round limb scales, and large and longitudinally rectangular caudal scales that constitute the caudal w horls.This new finding provides us with more information on the lepidosis of the Mesozoic .

Keywords: new , , skeleton, lepidosis, Early Cretaceous, western Liaoning .

Lizards are majo r groups in the Late Mesozoic Etymology:Liaoning , the province where the Jehol Biota of w estern Liaoning and the adjacent holoty pe w as collected ;lacerta (Latin), lizard . regions, no rtheastern China .Several lizards Brevi- (Latin), short ;rostra (Latin), snout . have been found from the Yixian Formation , the lower unit of the Early C retaceous Jehol G roup in Holotype :An articulated skeleton w ith its rig ht w hich the feathered theropods , primitive birds , early fo relimb and mid to posterior caudals missing (GM V mamm als and angiosperms were discovered in the past 1580 ; National Geological Museum of China , decade[ 1, 2] . The reported lizards include Beijing).Although most skeletal bones them selves tenuis[ 3—5] , Dalinghosaurus were lost , their moulds are fairly clear and very longidigitus[ 6 , 7] , and Jeholacerta formosa[ 8] , and anatomically informative (Fig .1). some other material has also been under study[ 9] . Locality and horizon:Huang banjigou , Beipiao , Recently , another new lizard specimen w as western Liaoning ;Yixian Formation . collected from the Yixian Fo rmation of a quarry near the village of Huangbanjigou , Beipiao , western Diagnosis:Skull broad with short , pointed Liaoning .This new finding further enriches our snout and large orbits .Naso-frontal suture at about know ledge on the taxonomic diversity and evolution the level of anterior bo rders of orbits .Frontals about lizards within the Jehol Biota .It should be paired.Jug al having long do rsal processes and in pointed out that the remarkable scale impressions contact w ith squamosal .Presacrals at least 26 or w ere preserved on the new specimen , representing more , w ith 19 do rsals included .Anterior caudals the second example follow ing the holoty pe of w ith one pairs of laterally directed transverse Jeholacerta formosa[ 8] . It provides important processes, first auto tomy septum on the 6th caudal. evidence for our understanding of the lepidosis Interclavicle cruciform and w ith long anterior features of the Mesozoic lizards . process.Pubis moderately elong ated .Hind limb fairly long compared with fo relimb .Distal end of tibia 1 Systematic paleontology slig htly concave .Large astragalus and relatively small calcaneum not co-ossified .M etatarsal II I equal to IV Squamata Oppel, 1811 Scleroglossa Estes, de Queiroz et Gauthier, 1988 in length .Pedal phalangeal fo rmula 2∶3∶4 ∶5 ∶4 . Liaoningolacerta gen .nov. Ventral scales small and mainly rhomboid in shape Liaoningolacerta brevirostra gen .et sp .nov. w ith the arrangement in transversal rows .Lateral

＊ Supported by National Natural Science Foundation of China (Grant No.40272008), the China Postdoctoral S cience Foundation (Grant No . 2003034012), and the Fund for Young Geologist of former Ministry of Geology and Mineral Resou rces(Grant No .Qn979827)

＊＊ Presen t address:Institute of Geology , Chinese Academy of Geological Sciences, Beijing 100037 , China.E-mail:jishu -an @sina.com Prog ress in Natural Science Vol.15 No .2 2005 w ww .tandf.co .uk/journals 163 scales very large and pavimentous.Scales covering and rectangular , forming caudal whorls . limbs tiny , round or polygonal .Caudal scales long

Fig.1 . Liaoningolacerta brevirostra gen .et sp .nov., holotype and its sketch (GMV 1580).(a)—(d)indicate the regions of scales shown in Fig .4.a, astragalus;c , calcaneum ;cv1 , 1st caudal verteb ra ;dr , dorsal ;dv1 , 1st dorsal verteb ra ;d3 , 3rd distal tarsal; d4 , 4th distal tarsal;fe, ;fi, fibula;hu , humerus;mtI , metatarsal I ;mtV , metatarsal V ;ra, radius;ral, radiale ;sv1 , 1st sacral ;ti, tibia;ul, ;ulr , ulnare ;I —V , pedal digit I —V .

2 Description

2 .1 Skull and low er jaw

The skull is broad w ith sho rt and somew hat pointed snout , large o rbits , and open supratemporal fenestrae (Fig .2). The skull length measures roug hly 9 .6 mm , 29 % the snout-vent leng th (33 .4 mm).The skull w idth is the g reatest (6 .7 mm)at the level just behind orbits, making the skull width / leng th ratio about 70 %.The o rbit is round and large w ith its diameter 2 .7 mm (28 % skull length).The right supratemporal fenestra appears oval and relatively large .

The shape of premaxilla is unknow n , w hile the is also difficult to be outlined exactly .There Fig .2 . Liaoningolacerta brevirostra gen .et sp .nov ., skull and are eig ht monocuspid teeth preserved on the left mandible.den , dentary ;fr , frontal;j, jugal;mx , maxilla ;n , premaxilla and maxilla with the anterior teeth nasal;orb , orbit;pal, palatine;po, postorbital;sq, squamosal; sm aller . stf, supratemporal fenestra . In the , the nasal is long and broad at its posterio r portio n .The straight naso-frontal suture 164 w ww .tandf.co .uk/journals Prog ress in Natural Science Vol .15 No .2 2005 slightly slopes medio-caudally , and lies about at the the dorsal are nearly com pletely preserved .They level of anterior borders of orbits .The paired frontals are long and very slender .The relationships of the are distinctive in being relatively broad at the naso- anterio r several pairs with the sternum or frontal suture , but slightly constricted between the xiphisternum are uncertain because the latter tw o o rbits and becoming wider posteriorly . The were not identified .The middle pairs are longer , morphology of parietal remains unknow n because of follow ed by six pairs of shorter ribs on the posterior its damaged preservation . dorsals .

The sutures between the prefrontal and its adjacent 2 .3 Pectoral girdle and fo relimb bones are not identified .The same situation is also seen for the lacrimal, so the presence or absence of a lacrimal is The pectoral girdle is partially preserved , but the uncertain.The postorbital seems to be a slender bone interclavicle is quite complete .Only a small posterior tapering posteriorly .The very long and curved bone portion of each coracoid is clearly distinguishable , which constituting the lateral border of orbit is undoubtedly the shows an obviously arched ventral margin and a hook-like jugal.Its dorsal process is narrow and bears a pointed end process at the junction between the ventral and posterior margins.The left is a long and curved bone that is in contact with the postorbital and squamosal.The without other notable features to be identified . right squamosal is exposed with a long and tapering anterior process.Posteriorly , this bone extends medially The interclavicle is ty pically crucifo rm (3 .9 m m into a small parietal process and posterolaterally into a in total leng th ) w ith slender anterior and lateral small process for the quadrate .Fragments of the palatine processes.The anterior process is long (1 m m), and are able to be distinguished at the lateral border of left occupies roug hly 37 % of the length of the posterior orbit . process (2 .7 m m), the latter ends in a slig htly The left low jaw is quite slender w ith less pointed caudal end .The lateral process (1 .5 mm)is preserved morphological info rmation .The dentary is one and a half times the leng th of the anterio r process shorter than half the w hole jaw .Only three posterio r (Fig .3(a)). dentary teeth are preserved , showing visibly conical Only the left forelimb w as preserved with some shape . manual elements absent .The humerus is a sturdy 2 .2 Axial skeleton bone (75 %fumer)with distinctly expanded proximal and distal ends :the proximal width mo re than twice The appears to consist of at the mid-shaft w idth .The straig ht ulna and radius are least 26 presacral vertebrae (including 19 dorsals), g racile and sho rter (68 % humerus) w ith slig htly tw o sacrals and an unknow n number of caudals .All broad ends proximally .These tw o bones are almost the vertebrae are distinctly procoelous .The last five the same in length and w idth .Only radiale and ulnare cervicals are visible .Although no mo re detailed are clear in carpus, the former is elongated and the features can be identified on them , it is suggested latter nearly round .The preserved metacarpals are that the first preserved cervical is not atlas or .So more robust than the preserved manual phalanges. the number of cervicals would be estim ated at least The phalanges are gracile , and the claw s quite small . seven or more .Dorsal vertebrae are generally longer than cervicals , and the last five or six do rsals more massive .Sacrals possess broad and long transverse processes that may be fused at their tips .The first sacral is much larger than the second .Only eight vertebrae of the caudal series w ere preserved .The anterior caudals are non-autotomous and bear developed transverse processes pointing laterally , decreasing in length quite rapidly from the first to the Fig .3 . Liaon ingolacerta brevirostra gen .et sp .nov., (a) six th (very small). septa probably begin pectoral and (b) pelvic girdles.cl, clavicle ;co , coracoid ;ic, from the six th caudal. interclavicle;il, ;is, ;pu , pubis.

The last five cervicals bear visible ribs that are 2 .4 Pelvic girdle and hind limb short and expanded at their ends .Nineteen pairs of Prog ress in Natural Science Vol.15 No .2 2005 w ww .tandf.co .uk/journals 165

The three pairs of the pelvic bones are loosely Table 1 . Lengths of some left girdle and limb bones (mm) connected and clearly unfused together .The ilium has Humerus 4 a long slender blade that gradually tapers caudally . Ulna 2 .7 The pubis is slig htly shorter but slightly wider than Radius 2 .7 ilium .It is apparently curved and its anterior portion Ilium 2 .9 slightly narrow . A somew hat prominent pubic Pubis 2 .6 tubercle is visible (Fig .3(b)).The ischium seems to Femu r 5 .3 be a quite broad bone w ith its exact morphology Tibia 3 .8 unknow n . Fibula 3 .7 M etatarsal I 1 .5 The femur is robust and of moderate length M etatarsal II 2 .2 (roug hly 16 % of snout-vent leng th).This bone is M etatarsal III 2 .8 just w eakly curved .The w ide tibia and slender fibula M etatarsal IV 2 .8 are shorter (70 %—72 % femur)and nearly straight . M etatarsal V 0 .9 In the left hind limb , the ends of tibia and fibula are Pedal digit III 4 .6 expanded , making an obvious space betw een the two Pedal digit IV 7 .2 bones .The distal end of tibia seems w eakly concave . Pedal phalanx IV-1 2 .5 In the ankle , the oval or round astragalus and calcaneum are no t co-ossified , indicating perhaps the 2 .5 Scale impressions juvenile condition . The very large astragalus is Fortunately , large-area epidermal scale articulated w ith the entire distal end of tibia .Two impressions w ere w ell preserved at neck , body , limb distal tarsals are identified , the 4th is slig htly smaller and tail ventrally (Fig .1).All scales are imbricate , than the calcaneum and the 3rd tiny .The second w ith the sizes and shapes varying at different parts. distal tarsal is apparently absent . There is no evidence of the presence or absence of osteoscutes . The foot is long w ith the total leng th of metatarsal IV and digit IV about 1 .9 times the femur The body ventral scales are small and basically leng th .The metatarsals show the common lizard rhomboid , arranged in row s more transversally than condition w ith the 5th very short and hooked .The longitudinally .There seems to be more than 70 o ther metatarsals are long and slender (Table 1), transversal row s of the ventral scales betw een the their ends ex pand proximally and distally .The 3rd pecto ral and pelvic girdles .There are 4 —5 pectoral metatarsal is equal to the 4th in length , but more scales in 1 mm leng th (Fig .4(a)).The abdominal slender than the 4th .The pedal phalangeal formula is scales are similar to pectoral scales in size and 2∶3∶4∶5∶4 , and the phalangeal lengths show the morphology , but slig htly enlarging laterally .One usual proportions (Fig .1).The 4th digit is more longitudinal row of the pavimentous and robust and much longer than others , w hile the length comparatively much larger lateral scales is clearly of the 3rd digit is slightly g reater than that of the preserved along the body lateral margin , in w hich the 5th .All claw s are sm all and sharp . largest may ex ceed 0 .8 mm long (Fig .4(b)).

Fig.4 . Liaoningolacerta brevirostra gen .et sp.nov., scales.(a)—(d)show the regions labeled in Fig.1 .(a)Pectoral scales;(b) abdominal and lateral scales;(c)postfemoral scales;(d)caudal scales.cv3 , the 3rd caudal vertebra ;cv5 , the 5th caudal vertebra;dr , dorsal rib ;fe, femur .

The scales covering the ventral neck and limbs are extremely small and nearly round o r irregularly 166 w ww .tandf.co .uk/journals Prog ress in Natural Science Vol .15 No .2 2005 polygonal .The number of the left postfemoral scales is on centra , fewer proximal caudals that bear evident average 8 —9 between the distance of 1 mm (Fig .4(c)). transverse processes , nearly straight femur , and The caudal scales are long and rectang ular in metatarsal I II as long as IV .In Yabeinosaurus , the shape , and comparatively large (apparently larger jugal does not com plete postorbital arch , the number than the ventral scales)w ith an average leng th of of dorsal vertebrae counts 20 , the body is apparently each scale roughly 0 .5mm .The width of each scale is long and slender[ 3, 5] , and the femur is relatively short about two-thirds of leng th of the corresponding scale . compared w ith the snout-vent leng th (Table 2 ). Three transversal row s of the caudal scales are These features are different from those of the roug hly equal to the two caudal vertebrae in length specimen reported in the present paper .Jeholacerta is (Fig .4 (d)).These caudal scales show regularly similar to the new lizard in the respects of small size , transversal rows in arrangement and constitute the procoelous vertebrae , short limbs , and caudal caudal w ho rls . scales[ 8] .But the differences are also considerable betw een the tw o :(1)the anterior po rtions of frontals 3 Comparison and discussion seem much longer befo re orbits in Jeholacerta ;(2) the pubis is rod-like and narrow only w ith two ends 3 .1 Comparison w ith other early lizards slig htly expanded in Jeholacerta ;(3) the femur is comparatively shorter but mo re robust in Jeholacerta Up till now , three further genera of lizard have than in the new lizard (Table 2);and (4) the also been know n from the Yixian Fo rmation of transversal row s of ventral scales and the scales w estern Liaoning and the adjacent regions : around mid-body are m uch few er in Jeholacerta than Yabeinosaurus , Dalinghosaurus , and Jeholacerta , in the new lizard .In comparison , the new specimen of w hich o nly Dalinghosaurus is relatively large . is different from the known lizards from the Early This described lizard can be disting uished from Cretaceous Yixian Form ation of no rtheastern China , Dalinghosaurus[ 6 , 7] in its less do rsal vertebrae (19 therefore represents another distinct genus and versus 20), relatively shorter and broader caudal species .

Table 2 . Some length ratios of the lizards from the Yixian Formation (%) Species Hu/ Fe Ul/ Hu Ti/ Fe Fe/S VL S pecimen Liaoningolacerta brevirostra sp .nov . 75 68 72 16 GMV 1580 (holotype) Yabeinosaurus tenu is 73 63 68 12e CNM M 3673 (holotype)[ 3] Yabeinosaurus tenu is 78 71 71 11e YFM-R002 (neotype)[ 5] Dalinghosa urus longidigitus 70 69 80 — IG-02-7-16-2[ 7] Jeholacerta formosa 83 70 80 12e GMV 2114 (holotype)[ 8] Fe, femu r;Hu , humerus;S VL , snout-ven t length ;Ti , tibia ;Ul, ulna.e , estimated value;— , unknow n value .CNM M , former Central National Museum of Manchoukuo ;GMV , vertebrate fossil collection of the National Geological Museum of C hina, Beijing ;IG , Institute of Geology , Chinese Academy of Geological S ciences, Beijing ;YFM-R, fossil collection of the Yizhou Fossil Museum , Yixian , Liaoning . Lizards were also spread w orldw ide during the several genera have been put at the position of periods of Late and Early Cretaceous outside Squam ata on the basis of recent cladistic China[ 10 , 11] . Although a lo t of materials are analyses[ 11 , 17—19, 21] . represented only by the isolated elements , several quite com plete and fully articulated skeletons have In Scandensia , the vertebral centra are also been know n . The list essentially includes : amphicoelous , interclavicle rhom boid , penultimate [ 17] , , and phalanges slender and elongated . In Palaeolacerta from the Upper Jurassic () , the premaxilla is elo ngated Solnhofen limesto nes of Germany[ 10, 12 —14] ; anterio rly , snout long and narrow , frontals fused and Sharovisaurus from the Upper Jurassic extremely broad posteriorly , vertebrae amphicoelous, (Kimmeridgian ) of Karatau in Kazakhstan[ 15] ; presacrals 24 in number , and interclavicle T- [ 19] Meyasaurus , Scandensia and Hoyalacerta from the shaped .These two basal lizards show m any Lower Cretaceous (Barremian)Las Hoyas locality of rem arkable differences from the new Liaoning Spain[ 16—18] ; and Huehuecuetzpalli and material.In Meyasaurus , the snout is relatively Tepexisaurus from the Lower Cretaceous ()of long , frontal single and having three processes Tepexi de Rodrí guez in Mexico[ 19 , 20] .Of these tax a , anterio rly , dorsal vertebrae 17 in number[ 16] .In Prog ress in Natural Science Vol.15 No .2 2005 w ww .tandf.co .uk/journals 167

Tepexisaurus , the lower jaw is very robust , presacral (10 ) are the synapomorphic characters of column consisting of 23 vertebrae , and the body Scleroglossa[ 22 , 23] .So Liaoningolacerta should be covered with the small g ranular scales[ 20] .These two included w ithin the taxon Scleroglossa .Furthermore , scincomorph lizards can also be distinguishable from this new lizard show s some differences from Gekko ta ; the new Liaoning lizard .The Solnhofen lizards were in the latter the vertebral centrum is mainly ever included within the clade [ 10, 12] , but amphicoelous and the body covered mostly w ith recent analyses indicate their basal or uncertain g ranular scales . Characteristics of osteological position of Squamata[ 11, 17 , 21] .The new Liao ning anatomy and lepidosis in Liaoningolacerta most lizard differs from Bavarisaurus and Palaeolacerta in probably indicate its close relationship w ith having the procoelous vertebral centra , and from . Bavarisaurus further in cruciform interclavicle and much sho rter tibia com pared with femur[ 10, 14] . 3 .3 Lepidosis of early lizards M oreover , it also differs from Ardeosaurus and Eichstaettisaurus in the fact that (1) Ardeosaurus The lepidosis characteristics are accepted as one has the relatively small orbits, long portions of of the most primary features to diagnose different clades (including families and genera) of ex tant frontals before orbits , and 23 —25 presacrals , and lizards[ 24] .But scales o r their impressions are very (2)Eichstaettisaurus possesses a comparatively broad and rounded snout , fused frontals , 31 presacrals , and difficult to be preserved in fossil lizard g roups .It is relatively short manus and pes[ 10 , 13] .As stated rem arkable that two lizard skeletons with most of the above , I am co nvinced that the new Liaoning lizard scale impressions were discovered from the Early Cretaceous Yixian Form ation of no rtheastern China : described here represents exactly a new genus and [ 8] species , and name it Liaoningolacerta brevirostra . Jeholacerta , and Liaoningolacerta repo rted in the present paper .These findings give us more valuable 3 .2 Phy logenetic position info rmation about the lepidosis features of the Mesozoic lizards .In these two lizards , the body M odern lizards are currently divided into four ventral scales are rhomboid and imbricate in major groups :Ig uania , Gekkota , Scincomorpha and arrangement , w hile the caudal scales longitudinally Anguimo rpha .It is w idely accepted that the Iguania rectangular and forming the caudal w ho rls .Compared is the sister taxo n to the other three groups that w ith those of Jeholacerta[ 8] , the ventral scales are together constitute the Sclerog lossa ;furthermore , much sm aller in Liaoningolacerta , suggesting m uch Gekkota is placed as the sister taxon of more transversal row s of the ventral scales and m uch (Scincomo rpha plus Anguimo rpha) more scales around mid-body in latter genus .The w ithin Scleroglossa[ 22] despite another hypothesis [ 23] holoty pe of the Sharovisaurus from proposed . Kazakhstan is also a nice example with w ell-preserved [ 15] In Liaoningolacerta , the very small size , non scales .Its caudal scales show m any similarities to co-ossified astrag alus and calcaneum , and loosely those of Jeholacerta and Liaoningolacerta in connected pelvic elements perhaps indicate the morphology and arrangement .The Early Cretaceous juvenile condition of this specimen .Whereas this Huehuecuetzpalli and Tepexisaurus from Mexico lizard show s many determined features that are were preserved w ith a few granular scales that are significant for analyzing the lizard phy logeny .The extremely small , round in shape , and irregular in [ 19 , 20] features include :(1) frontals paired ;(2) jugal arrangement .It comes to the conclusion that meeting squamosal ; (3 ) vertebral centrum the lepidosis in early (Mesozoic)lizards also show procoelous;(4)presacral vertebrae 26 or more in many differences betw een genera or even higher taxa number ;(5 ) a single pair of caudal transverse as in the ex tant lizards . processes;(6)caudal autotomy septa present ;(7) Acknowledgements Special thanks are given to Dr.Ji interclavicle crucifo rm w ith large anterio r process ; Qiang (Institute of Geolog y , Chinese Academy of Geolog ical (8)pubis moderately elong ated ;(9)hind limbs w ell- Sciences), Dr.Ren Dong (Capital Normal U niversity)and Dr. developed ;(10)distal end of tibia w eakly notched ; Lu Liwu (National Geological M useum of China)for their helps (11)ventral scales rhomboid and imbricate ;and (12) in the fieldwork . caudal scales longitudinally lo ng and fo rming caudal w horls.Among above features , (4), (7), (8)and References 168 w ww .tandf.co .uk/journals Prog ress in Natural Science Vol .15 No .2 2005

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