Intro

The LB1 cranium, along with the post-cranium, was recovered in September 2003 during archaeological excavation at Liang Bua, a limestone cave on Flores in eastern Indonesia 14 km north of Ruteng(the provincial capital of Manggarai Province). The age of LB1 ranges between 60.000 years ago (kyr) and 100.000 kyr [1]. As far as the skull is concerned, while the mandible is almost complete (apartthe left condyle), the bregmatic region, right frontal, supraorbital, nasal and sub-nasal regions were discovered damaged [2]. Moreover, LB1 shows cranial asymmetry, which has been considered bysome authors to be similar to that observed in non-pathological African ape and fossil hominin crania, but by others as positional deformational plagiocephaly, a condition that results from plasticdeformation of the skull during infancy. Overall, even though the LB1 skull is mostly preserved, the fragmented and missing regions of the cranium coupled with the alleged physiological cranialasymmetry (post-depositional deformation cannot be entirely dismissed), a digital reconstruction is required in order to use the specimen for morphometric and biomechanical analysis. In thiscontribution we present a virtual reconstruction of the H. floresiensis holotype (LB1) cranium using state of-the-art three-dimensional (3D) digital modelling and GM methods [3].

Digital reconstruction of the LB1 H. floresiensis craniumAntonino Vazzana1, Justin A. Ledogar2, Rita Sorrentino3,1, David Strait4, Stefano Benazzi1,5

1 - Department of Cultural Heritage, University of Bologna, Ravenna, Italy. 2 - The Function, Evolution, and Anatomy Research (FEAR) Lab, School of Environmental and Rural Science, University of New England, Australia. 3 - Department of Biological, Geological, and Environmental Sciences, University of Bologna, Italy. 4 – Department of Anthropology, Washington University in St. Louis, St. Louis, USA. 5 - Department of Human Evolution, Max Plank Institute for Evolutionary Anthropology, Leipzig, Germany.

AcknowledgementsWe thank ARKENAS, Thomas Sutikna, E. Wahyu Saptomo, Peter Brown, the late Michael J. Morwood, and William L. Jungers for accessto digital data. This project was funded by the European Research Council (ERC) under the European Union's Horizon 2020 Researchand Innovation Programme (http://www.erc-success.eu/) grant agreement No 724046 - SUCCESS awarded to Prof. Stefano Benazzi.

This new reconstruction provides the opportunity to adjust and/orintegrate previous cranial measurements and is suitable for furtherquantitative studies, such as assessing cranial morphological variationusing GM methods or testing hypothesis of feeding behaviour by means offinite element analysis.

Step 5: Integration of missing parts

Step 1: Data Segmentation

Step 3: Reference (semi)landmark configurations

Step 6: Symmetrization

Step 4: TPS interpolation

Unpaired landmarks Paired landmarks* Curve names N Smlm count**

Basion (ba) Orbitale (or) Lower zygomatic arc right 1 20

Opistion (o) Foramen infraorbitale (fori) Temporal line right 2 19

Stafilion (sta) Superior orbital notch (son) Upper zygomatic arc right 3 20

Incisive foramen (if) Frontotemporale (ft) Orbital rim right (or to son) 4 9

Glabella (g) Jugale (ju) Orbital rim right (son to or) 5 9

Inion (i) Porion (po) Anterior nasal aperture left 6 10

Rhinion (rh) Anterior eminence (ae) Anterior nasal aperture right 7 10

Anterior nasal spine (ans) Mastoid process (mp) Orbital rim left (or to son) 8 9

Condylus occipitalis posterior (cop) Orbital rim left (son to or) 9 9

Entoglenoid (eg) Temporal line left 10 19

Upper zygomatic arc left 11 20

Lower zygomatic arc left 12 20

Midsagittal 13 39

Rhinion to glabella (Sellion) 14 9

Median nucal line 15 9

Palatine suture 16 9

Rhinion to Incisive foramen 17 9

Basisphenoid 18 10

Internal alveolar rim right 19 10

Internal alveolar rim left 20 10

External alveolar rim right 21 10

External alveolar rim left 22 10

Total landmarks 28

Total semilandmarks on curves 299

Total semilandmarks on serface 542

Total 869

* Landmarks identifiable on the left and right sides.

** Semilandmarks identified on the curves.

Results and Conclusions

Misures (mm) This study Kaifu et al. 2011 [10] Brown et al. 2004 Definition

Maximum cranial length 138,97 -139 -143 Glabella–opisthocranion

Minimum frontal breadth 66,86 61 67 Frontotemporale-frontotemporale

Supramastoid breadth 112,38 114 113 Max. breadth across the supramastoid crests

Bi-asterionic breadth 92,42 92 -97 Asterion–asterion

Basion–bregma height 85,80 89 -89 Basion–bregma

Basion–nasion length 77,30 -78 -81 Basion–nasion

Basion–prosthion length 82,68 -85 -88 Basion–prosthion

Superior facial height 50 -55 -53 Nasion–alveolare

Outer bi-orbital breadth 87,97 88 88 Frontomalare temporale–frontomalare temporale

Orbital breadth (r/l) 32,70 33/– 32 Maxillofrontale–ectoconchion

Orbital height (r/l) 34,29 32/– 31 The maximum height between the upper and lower borders of the orbit

Nasal breadth 21,33 21 21 Max. transverse inner breadth

External palate breadth 51,13 52 52 Ectomolare–ectomolare

Step 2: MirroringMaterials and Methods

3D digital models of the externalcranial surface, endocranium,mandible, and upper and lowerteeth were obtained from theCT image data acquired byBrown and colleagues in April2004 (Step 1). The first stepentailed the reconstruction ofthe right zygomatic arch, leftsupraorbital bone and leftmandible by mirror imaging thepreserved side, that is usingmorphological information ofthe original specimen [4, 5](Step 2). Then, the remainingmissing parts (i.e., bregmatic,nasal and sub-nasal regions)were virtually restored bywarping a reference cranium,i.e. KNM-ER 1813 (H. habilis)using thin plate splineinterpolation [6, 7] (Steps 3, 4,5). Finally, a symmetric versionof LB1 cranium was obtainedusing reflected relabelling [8, 9](Step 6).

Craniofacial measurements of LB1.

Contact: antonino.vazzana2@unibo.it

References: [1] Sutikna, T., Tocheri, M.W., Morwood, M.J.,Saptomo, E.W., Jatmiko, Awe, R.D., Wasisto, S., Westaway, K.E.,Aubert, M., Li, B., Zhao, J.X., Storey, M., Alloway, B. V., Morley,M.W., Meijer, H.J.M., Van Den Bergh, G.D., Grün, R., Dosseto, A.,Brumm, A., Jungers, W.L., Roberts, R.G., 2016. Revisedstratigraphy and chronology for Homo floresiensis at Liang Bua inIndonesia. Nature. 532, 366–369 [2] Brown, P., Sutikna, T.,Morwood, M.J., Soejono, R.P., Jatmiko, Wayhu Saptomo, E., AweDue, R., 2004. A new small-bodied hominin from the LatePleistocene of Flores, Indonesia. Nature. 431, 1055–1061. [3]Smith, A.L., Benazzi, S., Ledogar, J.A., Tamvada, K., Pryor Smith,L.C., Weber, G.W., Spencer, M.A., Lucas, P.W., Michael, S.,Shekeban, A., Al-Fadhalah, K., Almusallam, A.S., Dechow, P.C.,Grosse, I.R., Ross, C.F., Madden, R.H., Richmond, B.G., Wright,B.W., Wang, Q., Byron, C., Slice, D.E., Wood, S., Dzialo, C.,Berthaume, M.A., van Casteren, A., Strait, D.S., 2015. The FeedingBiomechanics and Dietary Ecology of P aranthropus boisei. TheAnatomical Record. 298, 145–167. [4] Besl, P. J. & McKay, N. D. Amethod for registration of 3-D shapes. IEEE Trans Pattern AnalMach Intell 14, 239–256 (1992). [5] Zhang, Z. Iterative pointmatching for registration of free-form curves and surfaces. Int JComput Vis 13, 119–152 (1994). [6] Gunz, P., Mitteroecker, P. &Bookstein, F. L. in Modern Morphometrics in PhysicalAnthropology 73–98 (Kluwer Academic Publishers-PlenumPublishers, 2005). doi:10.1007/0-387-27614-9_3. [7] Bookstein, F.L. Morphometric tools for landmark data : geometry and biology.(Cambridge University Press, 1997). [8] Mardia, K. V., Bookstein, F.L. & Moreton, I. J. ‘Statistical assessment of bilateral symmetry ofshapes’. Biometrika 92, 249–250 (2005). [9] Rohlf, F. J. & Slice, D.Extensions of the Procrustes Method for the OptimalSuperimposition of Landmarks. Syst Zool 39, 40 (1990). [10] Kaifu,Y. et al. Posterior deformational plagiocephaly properly explainsthe cranial asymmetries in LB1: A reply to Eckhardt andHenneberg. Am J Phys Anthropol 143, 335–336 (2010).

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