Transverse histological sections of the late juvenile tibia of <i>Gladocephaloideus jingangshanensis</i> (JPM 2014–004) viewed with transmitted light microscopy.

<p><b>A.</b> The cortex of a lower midshaft of the left tibia; not a rich vascularization. <b>B.</b> Close-up of the outer midshaft dominated by vascular canals directed longitudinally and radially. <b>C.</b> Magnified view of the middle cortex showing bulky lacunae embedded in the woven bone matrix with randomly arranged collagen fibres. <b>D.</b> Close-up of the inner cortex containing longitudinal, laminar and radial vascular canals; note the innermost radial canal connecting the cortex with the medullary cavity. <b>E.</b> Magnified view of the cortex rimmed with a thicker endosteal lamina lacking any laminar texture; note eroded innermost surface of the cortex. Abbreviations: cofi, collagen fibres; eol, endosteal layer; erl, endosteal resorption line; ipovc; incomplete periosteal vascular canal; la, osteocyte lacuna; lavc, laminar vascular canal; lovc, longitudinal vascular canal; pros, primary osteon; po/me-vc, periosteal-medular vascular canal; povc, periosteal vascular canal; ravc, radial vascular canal.</p

New Material of the Pterosaur <i>Gladocephaloideus</i> Lü et al., 2012 from the Early Cretaceous of Liaoning Province, China, with Comments on Its Systematic Position - Fig 2

<p><b>Photograph (A) and line drawings (B) of <i>Gladocephaloideus jingangshanensis</i> (JPM 2014–004).</b> Abbreviations: ca, carpals; cr, coracoids; cv, cervical vertebrae; d, dentray; dg, deep groove along the mid-line of the mandibular symphysis; dv, dorsal vertebrae; dr, dorsal ribs; etp, extensor tendon process; f, frontal; fc, fifth carpal; fe, femur; fi, fibula; fin, fingers; h, humerus; il, ilium; m, maxilla; mmttsI-IV, metatrals I-IV; mttv, metatarsal V; nao, nasoantorbital opening; or, orbital; pcr, parietal crest; pm, premaxilla; pt, pteroid; ra, radius; rdl, radiale; sc, scapula; st, sternum; sl, sclerotic rings; t, teeth; tc, tooth sockets; ti, tibia; ul, ulna; wm, wing metacarpal; wph1-4, wing phalanges 1–4. Scale bar = 5 cm.</p

A map of the fossil locality of <i>Gladocephaloideus jingangshanensis</i> (JPM 2014–004).

<p>The green solid pentagon (near Yixian County) represents the holotype locality.</p

New Material of the Pterosaur <i>Gladocephaloideus</i> Lü et al., 2012 from the Early Cretaceous of Liaoning Province, China, with Comments on Its Systematic Position

<div><p>Although there are nine genera of ctenochasmatoids reported from the Jehol Biota, at present each is known from a specimen that has either a skull or a relatively complete postcranial skeleton. A nearly complete juvenile specimen of <i>Gladocephaloideus</i> from the Lower Cretaceous Jiufotang Formation of Sihedang, Lingyuan of Liaoning Province is the most complete ctenochasmatoid preserved to date with a skull and postcranial skeleton. Based on the holotype (IG-CAGS 08–07) and the nearly complete new specimen (JPM 2014–004), the diagnosis of <i>Gladocephaloideus</i> is amended: approximately 50 teeth in total with sharp tips; small nasoantorbital opening, occupying approximately 13% of total skull length; ratio of prenarial rostrum length to skull length approximately 0.63; deep groove along the mid-line of the mandibular symphysis; length to width ratio of the longest cervical vertebra = 4.1; ratio of femur length to tibia length = 0.61; tibia as long as the wing-phalange 1. Phylogenetic analysis recovers <i>Gladocephaloideus</i> within the clade Ctenochasmatidae. <i>Gladocephaloideus</i> has a closer relationship to the Chinese <i>Pterofiltrus</i> rather than to other ctenochasmatid pterosaurs. Microstructure of limb bones implies that JPM 2014–004 represents an early juvenile of <i>Gladocephaloideus jingangshanensis</i>, and that the type specimen is not a fully grown specimen either. We assume that the holotype may equate to the late juvenile or sub-adult developmental stage of <i>Gladocephaloideus</i>.</p></div

Life reconstruction of <i>Gladocephaloideus jingangshanensis</i> (drawn by Zhao Chuang).

<p>Life reconstruction of <i>Gladocephaloideus jingangshanensis</i> (drawn by Zhao Chuang).</p

Strict consensus of 3024 most parsimonious trees obtained by TNT, based on analysis of 67 ingroup and 117 characters, showing the phylogenetic position of <i>Gladocephaloideus jingangshanensis</i> (Tree length = 461, consistency index = 0.356 and retention index = 0.760).

<p>Character and state distributions at key nodes are as follows: Monofenestrata, 6 (2), 13(2), 14(2), 17(1), 20(1), 95(0), 118 (1); Pterodactyloidea, 66 (1), 70(1),71(1),72(0),89(3),116(1); Archaeopterodactyloidea,29(1), 30(1), 32(1), 34(2), 64 (1),104(1); Ornithocheiroidea,63(1), 87(1), 93(1); Pteranodontia,22(1),25(1), 69(1), 78(1), 86 (1), 89 (3),90 (1), 95 (1), 98 (2), 108(1), 113 (2). Ctenochasmatoidea, 65(1), 67(1), 68(2); Ctenochasmatidae,5(1), 60(1); Azhdarchoidea, 47 (0), 54(1), 107(1), 110(1), 112 (1). Numbers adjacent to each node are Bremer support values. Liaoning ctenochasmatid pterosaurs are in red.</p

Transverse histological sections of the tibia of an early juvenile individual of <i>Gladocephaloideus jingangshanensis</i> (JPM 2014–004) viewed with transmitted light microscopy.

<p><b>A.</b> The cortex of the midshaft of the left tibia composed of numerous premature primary osteons enclosing longitudinal vascular canals. <b>B.</b> Close-up of the inner midshaft cortex showing presence of a single secondary osteon and bulky osteons with radially projected lacunar canaliculi; note thin endosteal bone that rims the medullary cavity. <b>C.</b> Close-up of the outer midshaft cortex formed by osteons randomly embedded in the woven bone matrix; note that some canals are open onto the outer periosteal surface. Abbreviations: eol, endosteal layer; erl, endosteal resorption line; ipovc; incomplete periosteal vascular canal; la, osteocyte lacuna; laca, lacunar canaliculi; lavc, laminar vascular canal; lovc, longitudinal vascular canal; osla, osteonal lacuna; oslam, osteonal lamella; pros, primary osteon; prvc, primary vascular canal; ravc, radial vascular canal; seos, secondary osteon.</p

Transverse histological sections of the late juvenile tibia of <i>Gladocephaloideus jingangshanensis</i> (IG-CAGS 08–07) viewed with polarized light microscopy.

<p><b>A.</b> Close-up of the outer cortex of the left tibia showing bundles of parallel and randomly distributed collagenous fibers. <b>B.</b> Close-up of the middle part of the cortex showing high density of collagenous fibers associated with the haversian bone; note relatively low number of interosteonal globular and ovoid lacunae; note flat osteonal lacunae. <b>C.</b> Close-up of the inner part of the cortex showing radial microfractures filled with sediment; note sediment depositions between the endosteal layer and the innermost cortical bone. <b>D.</b> Magnified view of the eroded innermost cortex and laminated endosteal layer. Abbreviations: cofi, collagen fibers; eol, endosteal layer; erl, endosteal resorption line; iosla, interosteonal lacuna; la, osteonal lamella; lovc, longitudinal vascular canal; os-cofi; osteonal collagen fibres; pros, primary osteon; ravc, radial vascular canal; s, sediment.</p

Transverse histological sections of the late juvenile tibia of <i>Gladocephaloideus jingangshanensis</i> (IG-CAGS 08–07) viewed with transmitted light microscopy.

<p><b>A.</b> The thin cortex of an upper part of the midshaft of the right tibia. <b>B.</b> Close-up of the cortex profile dominated by high density of longitudinal, occasionally anastomosing, vascular canals embedded in the woven bone matrix. <b>C.</b> Close-up of the outermost cortex showing numerous vascular canals that open onto the periosteal surface. <b>D.</b> Magnified view of the eroded secondary osteon (note considerably flattened lacuane) and an initial erosion of the neighboring primary osteon. <b>E.</b> Magnified view of undulated and serrated innermost cortical surface documenting erosional activity; note laminated character of the endosteal bone. Abbreviations: anvc, anastomosing vascular canal; ec, erosional cavity; eol, endosteal layer; erl, endosteal resorption line; ipovc; incomplete periosteal vascular canal; la, osteocyte lacuna; labt, lamellar bone tissue; ocel, osteoclastic erosion line; pros, primary osteon; povc, periosteal vascular canal; pros, primary osteon; seos, secondary osteon.</p

<i>Gladocephaloideus jingangshanensis</i> (JPM 2014–004).

<p>(A) Overview of the skeleton; (B) Close up of the skull; (C) Close up the anterior part of the rostrum, showing the deep groove along the mid-line of the mandibular symphysis; (D) Close up of the left pes and the right carpals. Abbreviations: dg, deep groove along the mid-line of the mandibular symphysis; fc, fifth carpal; rdl, radiale; ts, tooth sockets.</p