GEOL. CROAT. 50/2 I l43 - l46 1 1 ZAGREB 1997 Academician Milan Herak's Main Contribution to Palaeontology Branko SOKAC', Zlatan BAJRAKTAREVIC2 and Zlata JURISIC-POLSAK' The main contribut ion of Herak's palaeontological research carried out over a long period of time, began during his early career in the Geological-Palaeontologi­ cal Museum in Zagreb between 1943 and 1952. There­ fore his first publications concerned the field of palae­ ontology. Within that scientific discipline Herak made a significant contribution to the analysis of Triassic cal­ careolls sponges from the "Syconcs" group (HERAK, [943,1944). He investigated and presented the mor­ phological "characters" of five genera, and particularly those species where, on newly discovered material, he recognized some new features. He also established a new genus and species O/igop/ag/a cal"ll/ca . All previ­ ously known forms and their distribution were the sub­ ject of this Herak's paper with special emphasis on the vertical distribution and lithogenesis of the group. From a lithogenetic point, Herak highlights the genus Ambly­ sip/IOI/el/a, as well as the genera Oligoplagia and H%­ coc/ia. Herak also drew palaeoecological conclusions regarding the isolation of their habitat. He was only able to attr ibute stratigraphic value to two species: C%spol/gia dllbia (Upper Ladinian) and Amblysipho­ lIcl/a rimorica (Midd le Triassic). One of the most significant "nonalgal" papers of professor Herak deals with the palaeontology of the eave bear (Urs/ls spe/aclIs) and although published in 1947, remains undoubtrully valid. It is obvious that this work has been stimulated by the rich Museum collec ­ tion consisting or cranial vertebrae, long bones and teeth. This abundant osteological material was collected at various sites in Croatia (Medved a Cave ncar Lokve, Vindija, Bednik ncar Petrinja, Bobota, Vrapce, Cero­ vacke Caves and others). In his st udy HERAK (1947) used biometric analysis and described morphological features of teeth, comparing his results with variational curve of the total range of the speeies (EHRENBURG, 1935). This work represents a significant con tribution to the previous understanding of the most frequent Pleistocene animal remains in the Dinaric and eireum ­ Dinaric karst region. I Institute of Geology, Sachsova 2, P.O. Box 26g, I-IR-IOOOO Zagreb, Croatia. :'. Depanment of Geology and Palaeontology, Faculty of Science, University of Zagreb, UJ. kralja Zvonimira 8, HR-tOOOO Zagreb, Croiltiil. 3 Dcpartmcll1 of Gcology and Palaeontology, Croatian Museum of Natural I listory, Demetrova I, HR-I (X)()O Zagreb, Croatia. The greatest number of Herak's palaeontological works are related to the research of calcareous algae [rom Late Palaeozoic and particularly from the Triassic . This research has continued with variable intensity for over twenty years and resulted in Herak's numerous publications. After a relatively long "silent period" of research on the calcareous algae of shallow-water carbonates during World War II and afterwards, Herak started a new chap­ ter in the research of the calcareous algae, particularly the Dasycladaceac, Herak investigated various deposits from Croatia as wcll as from the former Yugoslavia, and thus he was among the first ones, together with Kochansky-Devid6, who initiated a new period of rese­ arch on fossil algae in Europe. 'They were later accom ­ panied by a number of authors from Zagreb where this kind of research has been traditional fo r more than a century. IJow is Herak's interest in the calcareous algae explained? Was it caused by the earlier discovery of, and research on the Upper Palaeozoic and adjacent Tri­ assic in Ml. Velebit, done in the Salopek's team, or Her­ ak's personal contact with Pia's works and algal mate­ rial during his stay in Vienna? Was it because our scien ­ tists arc predisposed towards the Triassic deposits or because of the idea that advancement in exploration or the Triassic is possible by detailed study of the calcare­ ous algae, especially the Dasycladaceae? The last ques­ tion reflects on the whole algae research of Herak which can be observed from two points of view: 1) taxonomic cont ributions and palaeontological consideration of sep­ arate genera and species and 2) the st ratigraphic, i.e. biostratigraphic aspects. This is related to the vertical range of a specific taxon, or the complete algal associa­ tion as well as their sig nificance in the stratigraphic attribution of certain sedimen ts or the recognition of contemporariolls facies. In his first paper concerning the calcareous algae he wrote about their stratigraphic and palaeontological s ig­ nificancc and stated some morphological characteristics (HERAK, 1950). He also surveyed particular clements This paper was presented at the scientific meeting dedicated to the 80th anniversary of the life of Professor Milan Herak, held on March 5th, 1997 in Zagreb 144 of their phy logeny and pointed out the recapitulation of some ontogenetic stages which are probably analogous to phylogenetic stages. Herak viewed at the fossil find s on the basis of their distribution, and characteri stics of the recent dasycl adacea n e nvironm ent which can be taken as facies and climatic indicators, showing their lithogenetic importance in the development of the car­ bonate deposits. He hi gh li gh ted the elements of algal structure which shou ld be observed, and explained the ir importance for reliab le determination, bearing in mind which characteristics arc essential and which Diles could be the consequence of adaptat ion. Herak indicted the relationship between the scientific diagnosis of the species and the number of researched i.e. observed samples, a nd lhe state of the original material which was used for primary descr iption and reconstruc tion. Thus almost all the basic questions concerning calcare­ ous algal research have bcen asked and they remain rel­ evant today, so that Herak's work functions as the noti ­ fication of the wo rking hypothesis which wi ll be rea­ lised in subsequent works. In this context Herak consi­ ders the genus Dip/opora in the association of Triass ic algae, w hi ch con tain s forms with a me taspondillous pattern of branches, while the other characteristics vary from spcc ics to spccics (HERAK, 1950). Herak trea ted the genus Dip/opora ancl the relationship between lheir particular species several times, adding new observa­ tions and understanding of the ir stratigraphic position and signi fi cance (HERAK, 1950,1956, 1957b, 1960, 1965). In these publications the distinction of the spe­ cies Dip/opora allllll/arissima and D. ({I1I1l//ala with dif­ ferentiated taxonom ic cr iteria was rea lised . Frequent discover ies of the species D. allllulatissima havc been made at numerous sites in Croatia, particularly in Lika, in an associati on which is characteristic for the Ladin­ ian (D. allllil/ata, Tcutlopore/ /a herc[{/ea etc.). Herak expanded the time span for this spec ies to the Ladinian, thus extendi ng the distribution of that species from a previous known An isian age, documented in the East­ ern and Southern Alps. Outside C roatia Herak' s achi­ cvemcnt was later L1sed in various stratigraphic intcrpre­ tations of the transit ional zone between the " Mendola" dolom ite to Buchenstein deposits in the range of the Sari dolomite in the Southern Alps, as well as the time span for Anisian and Ladinian equival ents in the Sile­ sian Triassic. Also, it was emphasized tha t part of the Welterstein depos its belong to the Upper Ladinian , cor­ responding to several sites in Mt. Velcbit. In a more extens ive analysis HERAK (l957b) di s­ cussed the problem of the species D. annulata which, according to Pi a included three varieties (dolomitica, septel/frioJlalis and debilis) and two form s of trichofora and vesicu lifera which he considered to be the result of sexual dimorphism. Refuting all three varieties founded on unproved hypothes is as well as the sex ual dimor­ phism, Herak relied on firm morphological distinctions of the species, and offered a new di vision of the species D. al/I/ulata into two subspecies . In one su bspecies he included speci mens with vesiculiferous branches and vcologta LfO;1I1Ca ;1\J/1. according to the priority principle he nominated it as D. allnu/ata subsp. dolomitica PIA and the second sub­ species included specimens with trichoform branches as a type species nominated as D. af/Illtlata subsp . al/llltla­ ta HERAK. I-Ie es tablished the time span for bo th sub­ species up to the Upper Ladinian and this has been later well documented at numerous sites in the Dinarides. HERAK (1965) ex tended his work on a detailed survey of the sites and morphological characteristics of severa l genera : Telttloporel/a, Macropore//a, Gyro­ porella, Oligopore//a , Physopore//a and Dip/opol'a and this enabled the el uc idation of the ir basic morphologi­ cal features and allowed determination of the relative stratigraphic positions as well as associations where the above taxa have been discovered. As in the case of D. aWl/tiata Herak prefered intraspecific category transfer­ ring the species D. hexaster and D. he{vetica, into the subspecies D. hexastcr subsp. hexasler and D. hex((sfer subsp. helvetica on the basis of poorly developed sha­ pes at the end s of the branches. Besides his first determinations of various genera in the Dinarides and their stratigraph ic distribution, Herak was also concerned about phylogenetic relationshi ps as well as s ignificance of morphological characterist ics in taxonomy. Herak was well aware of many difficulties in phylogenet ic reconstructions within various taxa, and thus he exploited the significance of morphological fea­ tu res in taxonomy. Herak is critical of the usage or small and gradual morphological differences in the delineation of taxa and he is of the opinion that estab­ lishment of subspecific variation is m ore appropriate than the foundation of new taxa, as such units could be more easily revised and defined. With the introduction of such a theore tical approach Herak emphasized the neccssity of application of the taxonomic criter ia and his theoretical frameworks are st ill val id. Herak considered calcareous algae and thei r impor­ tance in the st rati g raphy or the Late Palaeozoic and Mesozoic of the Dinaridcs in several papers (H ER AK, 1960, 1966). Along with listing SilCS in Dinarides where aJi previously cstablished species of gymnoeodi­ acean, cod iaeean and dasycladaeean al gae have been discovered, and their stratigraphic position, he added new data with es tablished changes to stratigraphic dis­ tribution. For several spec ies, he extended thei r strat i­ graphic range, considered the range previously known (e.g. Permocalculus fene//us has been extended to Early Permian, etc.), and he also commented upon the taxon­ omy of the genera Anthracoporella, Vermiporcl /a, Per­ mocalculus, EpimastojJora , etc . For severa l species of the genus Perrnocalcu!us (P . fragi/is, P. mOllo/i/ol'llIis and P. sofidus) Herak considered unifying them unde r the Ilame P.fragilis. In his overviews, presented also at international meetings, Herak has integrated the results prev iously achieved by several authors, which enabled the European algal society to become acquainted with Croatian ranges and our contribution to the research of the fossil calcareous algae at the critical time. SOk:10, Bajraklan;vic & JllI-i.~ic - l'olibk: AC:ldcmician Milan Herak 's Main Contriblilion to Palaeontology 145 As a competent and established expert in calcareous algae, Herak has worked on the taxonomic and strat i­ graphic intcrprctation of samples from Slovenia, Aus­ tria and Greece, incorporating his results into the inter­ pretation of regional gcological scttings as a base for speculations over the tectonic and hydrogeologic set­ tings, He has described sevcral species, subspecies and variations or dasycladacean algae, especially the Trias­ sic ones, These include Physopore/la mil/ut%idea HERAK 1967; Ph. likallo HERAK 1965; P/I. croalial HERAK 1958; DiplofJora su/Jrilis PIA val'. gracca HE­ RAK 1967; D. 0111111/010 subsp. annillara (PTA 1920) HERAK 1957; D. annll/ala subsp. d%milica HERAK 195 7 and Cayellxia medilerranea HERAK 1967 from the cyanophycean group. As previollsly mentioned, most of Herak's papers havc bcen dirccted toward stratigraphic dctermination, defining the distribution and mutual re lationship bet­ ween previously poorly defined complexes of deposi ts and their facies in the Late Palaeozoic, and particularly the Triassic. This understandi ng of fossil calcareous algae has enabled for the first time the definite div ision of the Middle Triassic of the part of Lika below the Velebit ML; the establishment of the Anisian and Lacii­ nian at numerous localities in the Outer Dinarides; the development of clastic facies of both the Middle Trias­ sic stages, as well as defi ning the entire range of certain taxa and whole algal communities. Also, all of these papers, even smaller volumes, contain some palaeonto­ logic and taxonomic novelties. Reports of the finds of some species, including isolated species, in the area of the Dalmatinska Zagora, Lika, Kordun, Hrvatsko Zago­ rje and the mountain s of Slavonia, arc also valu able because these finds stimulated later researchers to col­ lect this precious material, enabling more comprehen­ sive elaboration or calcareous algae with in the entire Mesozoic and even pan of the Palaeogene. The "algae" Sphacrocodilll1l borncl1Iallni ROTH PLETZ (sec HER­ AK, 1952, 1957a) remains a valid indkator of shaliow­ sea sedimentation in the Upper Triassic due to its mor­ phology, defini tion of original palaeoenvironment, method of decay and visual characteristics. Significant papers from the algal opus of Herak are also the result of collaboration. In co-authorship with the late professor Y. Koehansky-Devide (HERAK & KOCI-IANSKY-DEYIDE, 1960; KOCHANSKY-DEY­ IDE & HERAK, 1960) the calcareous algae of the Late Palaeozoic of Velebit MI., as well as samples from the sites in Gorski Kotar , Slovenia, Serbia and Montenegro, were described. New taxonomic contributions were provided by description of the new genus and species C/avaporcI/a ca/icilorl1lis and several new species of previou sly known genera includ ing AnlhracoporeI/a I'ieilla, Mizzia corllllla, Epimasropora likana, E. a/pina and DljJ/opora plfsi/la. The morphogenetic comparison for the spec ies Anrhracopore//a specrahilis PIA and newly-described AI/lhracoporc/la vicina was shown . The comparative analysis of several species of the genus VCr/mj)orcl/a was carried out, suggesting that V. ve/ebit(lIIa is probably younger synonym of the species GYI1l17ocodilll1l bellerophonfis. The descr iption of the species Vcrmiporclla serbiccl PIA was expanded, and the genus Epimasropora, despite unclear morphogenet­ ic characteristics, was extended with two previously mentioned species (E. likalla and E. alpilla). The uncer­ tainty of the genus Hicorocodiul1I (H. elcganrc ENDO), the organization of which is atypical of dasycladacean algae, was highlighted. The paper by HERAK et al. ( 1977) entitled "The Development of the Dasyclad Algae through the Ages" is among the significant contributions in calcareous algae palaeontology, due to its eva/Ualion and observa­ tion of morphogenetic features of algal evolution along with consideration of the phylogeny. Based upon the 29 morphological features, accompanied by their age, the correlation of 80 suitable gcnera was carried out. The authors proved that the continuity level of a ccnain fea ­ ture corresponds with its regularity, and is opposite to the level of differentiation and specialisation, The atti­ tude that the increase in differentiation is the result of evol uti onary changes, and that fossil dasyc\adaceans could be gathered into several morphogenetic evolu­ tionary levels, with their rcpresentativcs dispersed in lime, has been expressed. Based upon these features, five groups havc been formed, which include some common characteristics. The sequence of the separated groups through the geological past, also shows the evo­ lution from the first group with the most primitive fea­ lures to the fifth group, the youngest, with differentiat­ ed and specialised feature s . Thc application of thesc features enabled not only the classification of the main genera of fossil dasyclad algae, but also the infilling of some gaps, by checking the type material of some doubtful genera. This paper has remained valid as an analysis of morphogenetic characteristics, their deve­ lopment, differentiation and specialisation in the phylo­ genetic succession, On the occasion of this anniversary, when we cele­ brate and acknowledge the long-standing, rich opus that academician Herak leaves us , we cannot emphasize enough his contributions to palaeontology and geology, especially in the field of calcareous algal research. Numerous citations of Herak's papers in Croatian and, even more often, foreign publications, as well as the na­ ming of several taxa after Herak by some authors, could serve to emphasise the acknowled gement and value of Herak's papers. These taxa are: Physopo/'c//a hcraki var. hcraki BYSTRICKY 1967; Ph. hcraki var. ICIll.lipo- 1'0 BYSTRICKY 1967; Cymopolia Ireraki GUSIC 1967, later denoted as a younger synonym of C, fIIayaclIse JOHNSON & KASKA 1965, after DELOFFRE & RADOTCTC (1978); Pe/raseu/a ?lreraki SOKAC & NTKLER 1969; /-Ierakel/a paradoxa KOCHANSKY­ DEY IDE 1970; Hexae//a Ireraki MILANOYlC 1989 and ASlcroca/ell/lls heraki SOKAC & GRGASOVTC 1998. Working on the fossil a lgae from several European localities and publishing his papers in several foreign 146 jourpals and occasional publications, professor Herak has offered the European and global palaeontological community an insight into the Croatian approach and achieved results in the palaeontological and stratigra­ phic investigations of the fossil calcareous algae. With his comprehensive, but also differentiated approach to the series of open questions in the field of taxonomic, phylogenetic and stratigraphic domain of fossil calcare­ OtiS algae, Herak has initiated and guided (together with professor Vanda Kochansky-Dev idc) the path whieh remains in the papers of later researchers, and which is today in the European algal community frequently cal!cd "The Zagreb algal school", His devotion to palaeontology is revealed in the preparation and publication of the textbook "Palaeob­ otany" (HERAK, 1953, 1963). Besides its assignment to the sllldents of geology and biology, the aim of this textbook was to introduce a wider society of readers to palaeobotanical issues, and to get them acquainted with the most typical plants from the geological past ancl their inlluence in geological processes. He also published many popular articles in "Priro­ cia", in the edit ion "Znanje i raclost", in "Zadruzni kalcndar" etc., acquainting everyone with the basic ide­ as ancl meanings of palaeontology, palaeobiology and geology in general. REFERENCES BYSTRICKY, J. (1967): Die obertriadischen Dasy­ cladazeen der Westkarpaten.- Geologicky Sbornik­ Geologica Carpathica, XVJII/2, 285-309, Bratislava. DELOFFRE, R. & RADOICIC, R. (1978): Algues cal­ caires (Dasycladales) du Paieocene de Slovonie (Yougoslavie).- Bull. des Cent. de Rech. Expl.­ Prod. Elf-Aquitaine, 2/1 , 61-95. EHRENBURG, K. (1935): Die pleistozanen Baren Bel­ gLens: 1. Die Baren von Hastiere.- Mem. Mus. roy. d'I-list. Nat. Belg., 64, Brtissel. G U~;]C , I. (1967): New Dasycladaceae from the Maestrichtian of BcSpelj near Jajce (Western Bosnia) (Nove dasikladaceje iz mastrihta Bespclja kod Jajea).- Geol. vjesnik, 20,117-126. HERAK, M. (1943): sec # I in Bibliography of Profes­ sor Milan Herak (this Vol., p.127-135). HERAK, M. (1944): see # 5 in Bibliography of Profes­ sor Milan Herak (this Vol., p.127-135). HERAK, M. (1947): see # 9 in Bibliography of Profes­ sor Milan Herak (this Vol., p.127-135). HERAK, M. (1950): see # II in Bibliography of Pro­ lessor Milan Herak (th is Vol., p.127-135). HERAK , M. (1952): sec # 14 in Bibliography of Pro­ fessor Milan Herak (this Vol., p.127-135). lieologl:l Croane:! :"lUlL HERAK, M. (1953): see # 16 in Bibliography of Pro­ lessor Milan Herak (this Vol., p.127-135). HERAK, M. (1956): see # 25 in Bibliography of Pro­ !'essor Milan Herak (this Vol., p.127-135). HERAK, M. (1957a): see # 31 in Bibliography of Pro­ lessor Milan Herak (this Vol., p.127-135). HERAK, M. (l957b): see # 32 in Bibliography of Pro­ fessor Milan Herak (this Vol., p.127-135). HERAK, M. (1958): see # 33 in Bibliography of Pro­ fessor Milan Herak (this Vol., p.127 - 135). HERAK, M. (1960): see # 40 in Bibliography of Pro­ fessor Milan Herak (this Vol., p.127-!35). HERAK, M. (1963): sec # 55 in Bibliography of Pro­ fessor Milan Herak (this Vol., p.I27-135). HERAK, M. (1965): sec # 63 in Bibliography of Pro­ fessor Milan Herak (this Vol., p.127-135). HERAK, M. (1966): sec # 67 in Bibliography of Pro­ fessor Milan Herak (this Vol., p.127-135). HERAK, M. (1967): see # 73 in Bibliography of Pro­ fessor Milan Herak (this Vol., p.I27-135). HERAK, M. & KOCHANSKY-DEVIDE, V. (1960): see # 43 in Bibliography of Profcssor Milan Herak (this Vol., p.127-135). HERAK, M., KOCHANSKY-DEVIDE, v. & GUS1C, I. (1977): see # 144 in Bibliography of Professor Milan Herak (this Vol., p.127- 135). JOHNSON, J.E. & KASKA, H.V. (1965): Fossil Algae from Guatemala.- Professional Contributions of the Colorado School of Mines, 4, 152 p., Goldcn. KOCHANSKY-DEVIDE, V. (1970): Die Kalkalgen des Karbons vom Velebit-Gebirge (Moskovicn lind Kasimovien) (Vapnenacke aJge karbona Velebita (moskovijen i kasimovijen)).- Palaeontologia jugo­ slaviea, 10, 32 p., Zagreb. KOCI-IANSKY-DEVIDE, V. & HERAK , M. (1960): see # 44 in Bibliography of Professor Milan Herak (this Vol., p.127-135). MILANOVIC, M. (1989): [-Iexaella heraki n. gen., n. sp. , a new problematical (incertae sedis) microfossil from the Lowe r Permian of Gorsb Kotar region (Croatia, Yugoslavia).- Geol. vjesnik, 42, 29-3 1. SOKAC, B. & GRGASOV1C, T. (1998): Astcrocalell­ Ius heraki n. gen., n. sp., a new calcareolls alga (Gy­ mnocodiaceae) from the Upper Triass ic Haupl­ dolomite of Zumberak, North Croatia.- Facies, 38, in press, Erlangen. SOKAC, B. & NIKLER, L. (1969): 0 vrstama roda Petrascula iz donjeg lijasa Vclebita (On the species of the genus Petrascula from the lower Liassic of Velebit).- Acta gcol., 6, (Prir. istrQz_ Jugosl. akad. znan. lImjtt., 36), !O3-112, Zagreb.